The Calculus Bible www.calcbible.com June 8, 2010 Introduction This document is not meant to be a textbook, but rather a review guide or a study aide for high school students who have completed the Advanced Placement AB Calculus curriculum. All other BC Calculus topics are separately outlined in The Calculus Bible, The New Testament by the same author. Part I Functions 1 Domain, Range, Asymptotes, and Fundamental Properties 1.0.1 Polynomials • 1.0.2 D = R Rational f (x) D = g(x) R {x: g(x) = 0} Vertical asymptotes • x = a, where a is an exclusion from the domain Horizontal symptotes • y = 0 if • y = ratio of leading coecients if g(x)is a higher order than f (x) f (x) and 1 g(x) are of same order 1.0.3 Trigonometric y = sin(x) • D = R • R = −1 ≤ y ≤ 1 y = sec(x) • D = x : x 6= • R = | y | R = odd integer nπ 2 odd integer where n is an ≥1 y = tan(x) • D = x : x 6= • nπ 2 where n is an R Identities • cos2 (x) + sin2 (x) = 1 • sin(2x) = 2sin(x)cos(x) • cos(2x) = cos2 (x)sin2 (x) • 1.0.4 2 tan (x) + 1 = sec2 (x) Inverse Trigonometric y = sin−1 (x) • D = −1 ≤ x ≤ 1 • R = −π 2 ≤y≤ π 2 y = sec−1 (x) • D = |x| ≥ 1 • R = 0≤y≤ π or 2 π≤y≤ 3π 2 y = tan−1 (x) • D = R • R = −π 2 <y< π 2 2 1.0.5 Exponential y = bx , b > 0 • D = R • R = y>0 • Remember: 1.0.6 y = bx ⇔ x = logb y Logarithmic y = logb x • D = x>0 • R = R Properties • logb (m + n) = logb m + logb n • logb ( m ) = logb mlogb n n • logb mr = rlogbm • logb 1 = 0 • logb bx = x • blogb x = x 2 Absolute Value • |f (x)| ips all points above the x-axis • f (|x|) makes the function even 3 Inverses • Found by switching the places of • Remember: y = logb x and y = bx x and y and solving for y are inverses, which means inverses 3 y = ln(x) and y = ex are 4 Odd and Even Functions 4.1 A function is odd if f (−x) = −f (x) ∀x ∈ D • Symmetrical with the origin • Polynomials with all odd powers (no constants, because 4 = 4x0 ) 4.2 A function is even if f (−x) = f (x) ∀x ∈ D • Symmetrical with the y-axis • Polynomials with all even powers 4.3 Remember, many functions are neither odd nor even 4 5 Graphs You Must Know y = bx , b > 1 y = bx , b < 1 5 y = logbx (includes y = ln(x)) 2 2 2 2 2 x √ + y = r (note: r is the radius, so 3x + 3y = 15 is a circle of radius 5 6 x2 a2 + y2 b2 = 1, a > b x2 a2 + y2 b2 = 1, a < b 7 x2 a2 yb2 = 1 2 y = x3 8 6 Zeroes of a function • Set the function • For cubics, nd any rational root, r, and synthetically divide by =0 and solve (xr) If you cannot nd a rational root, use Newton's method of approximation: n) xn ff0(x (xn ) xn+1 = 7 Symmetry • y-axis: (x, y) → (x, y) • x-axis: (x, y) → (x,y) • origin: (x, y) → (x, y) (non-function) • y = x: (x, y) → (y, x) 8 Limits 8.1 Theorems 1. Limit of a sum or dierence = sum or dierence of the limits 2. Limit of a product = product of the limits 3. Limit of a quotient = quotient of the limits (unless the limit of the denominator = 0) 4. Limit of the n th th root = n root of the limit 8.2 Limits you must know 1. 2. 3. 4. 5. 6. lim a = +∞, b→0+ b where a>0 and nite lim a = ∞, where a>0 and nite lim a = ∞, where a<0 and nite b→0− b b→0+ b lim a = +∞, b→0− b lim a b→±∞ b = 0, where where a a<0 and nite is nite 1 lim(1 + x) x = lim (1 + x1 )x = e x→0 x→∞ 9 8.3 Non-existent limits • ±∞us • limits which do not converge are non-existent limits • 1 a non-existent limit (lim 2 doesn't exist) x→0 x If Ex: limsin( x1 ) x→0 lim sin(x) and lim f (x) 6= lim− f (x) x→a+ then the limit does not exist x→a Ex: lim |x| x x→0 are non-existent (uctuates between 1 and -1) x→∞ does not exist 9 Continuity 9.1 Denition A function is continuous at a if f (a) exists and lim f (x) = lim− f (x) = f (a) x→a+ x→a 9.2 Theorems 1. If f (x) (a) and g(x) are continuous at f + g , f g , f × g , f ◦ g f (b) is continuous at g f (x) [a, b] 2. If is continuous on f (x) is f (x) = c 3. If c continuous on if c then are continuous at g(c) g(c) 6= 0 [a, b] , then [a, b] and f (x) has a maximum and a minimum value on f (a) < c < f (b) Part II Dierential Calculus 10 The Derivative 10.1 Denitions (you must know them!) 1. f 0 (x) = lim f (x+h)h f (x) 2. f 0 (a) = lim f (x)x fa (a) = lim f (a+h)h f (a) h→0 x→a (generates a slope function) h→0 10 then ∃ at least one x in [a, b] : 10.2 Theorems 1. d = c dx [f (x)] d [cf (x)] dx 2. Product rule: d dx h f (x) g(x) d [f (u)] dx d [u(y)] dx 5. Implicit: i = dy = u0 (y) dx 7. Rolle's Theorem: If then ∃c g(x)f 0 (x) f (x)g 0 (x) (g(x))2 = f 0 (u) du dx 6. Logarithmic: If y = f (x) d f (x)g(x) dx g(x)ln(f (x)) f (a) = 0 = f (x)g 0(x) + g(x)f 0 (x) d [f (x)g(x)] dx 3. Quotient rule: 4. Chain rule: where c is a constant in g(x) , then ln(y) = g(x)ln(f (x)) f (x) is continuous (a, b) : f 0 (c) = 0 8. Mean Value Theorem: If (a, b) : f 0 (c) = f (b)bfa (a) f (x) on d [ur ] dx 2. d [sin(u)] dx = cos(u) du dx 3. d [cos(u)] dx = sin(u) du dx 4. d [tan(u)] dx = sec2 (u) du dx 5. d [cot(u)] dx = csc2 (u) du dx 6. d [sec(u)] dx = sec(u)tan(u) du dx 7. d [csc(u)] dx = csc(u)cot(u) du dx 8. d [sin−1 (u)] dx = du √1 1u2 dx 9. d [tan−1 (u)] dx = 1 du 1+u2 dx 10. d [sec−1 (u)] dx = du √1 u u2 1 dx 11. d [au ] dx = au ln(a) du dx 12. d [eu ] dx = eu du dx 13. d [ln|u|] dx = rur−1 du dx = dy dx d = y dx g(x)ln(f (x)) = and dierentiable on (a, b) and f (b) = is continuous on [a,b] and dierentiable on (a,b), 10.3 Dierentiation Formulas 1. [a, b] and 1 du u dx 11 ∃c in 10.4 Dierentiability vs. Continuity • The fact that discontinuous f (x) at c For example, • For • Continuity f (x) is non-dierentiable at c is not sucient to conclude that f (x) is y = |x3| to be dierentiable at does not c, f (x) must be continuous at c necessarily imply dierentiability 11 Applications of the derivative 11.1 Slope of curve (a, b) = f 0 (a) The slope of a curve at point . Remember that (a, b) is on both the curve and the tangent line. 11.2 Slope of normal line The slope of the normal line at point (a, b) = −1 f 0 (a) 11.3 Curve Sketching 11.3.1 Increasing/Decreasing • If f 0 (x) > 0 then f (x) is increasing • If f 0 (x) < 0 then f (x) is decreasing 11.3.2 Critical Points • If f 0 (c) = 0 • If f 0 (c) 11.3.3 then (c, f (c)) is a critical point does not exist, then (c, f (c)) is a critical point Relative extrema x = c is a critical c, then (c, f (c)) is a point and x = c is a critical c, then (c, f (c)) is a point and f 0 (x) > 0 to the left of c and f 0 (x) < 0 to the right of to the left of c and f 0 (x) > 0 to the right of • If • If • If x=c is a critical point and f 00 (c) < 0 then (c, f (c)) is a relative maximum • If x=c is a critical point and f 00 (c) > 0 then (c, f (c)) is a relative minimum relative maximum f 0 (x) < 0 relative minimum 12 11.3.4 Inection points • If concavity changes, (f • If f 0 (x0 ) = 0 • If f 0 (x0 ) = ±∞ • If (c, f (c)) is • If 00 (x) changes sign) at the point (x0 , f (x0 )), then (x0 , f (x0 )) is an inection point then there is also a horizontal tangent at that point then there is also a vertical tangent at that point a critical point and f 0 (x) does not change sign at x=c , then (c, f (c)) is an inection point (x0 , f (x0 )) f 00 (x0 ) = 0. is an inection point, then Note: the converse is not neces- sarily true! 11.3.5 Concavity • If f 00 (x) > 0 on (a, b) then the graph of f (x) is concave up on • If f 00 (x) < 0 on (a, b) then the graph of f (x) is concave down on (a, b) (a, b) 12 Max-min word problems 1. Evaluate the function at the endpoints and at all critical points. 2. The largest value will be the absolute maximum and the smallest value will be the absolute minimum. 3. Remember, continuous functions have both an absolute maximum and an absolute minimum on a closed interval. 13 Motion along a line Go from x(t) → v(t) → a(t) by dierentiating. 14 Related Rates 1. Find an equation which relates the quantity with the unknown rate of change to quantitie(s) whose rate(s) of change are known. 2. Dierentiate both sides of the equation implicitly with respect to time. 3. Solve for the derivative that represents the unknown rate of change. 4. Then evaluate this derivative at the conditions of the problem. 13 Part III Integral Calculus 15 Antiderivatives 15.1 Denition F (x) is an antiderivative of f (x) if and only if F 0 (x) = f (x) 15.2 Applications 15.2.1 • Exponential growth and decay If you know that • k dy dt = ky then y = Cekt ⇔ y = y0 ekt where y0 = y(0) is the growth rate and may be given as a percent • Tdouble = 15.2.2 ln2 , k Thalve = ln2 k Dierential Equations 1. Separate the variables so that the equation reads f (y)dy = g(x)dx . 2. Integrate both sides, adding the constant to the side with the independent variable. i.e. ´ f (y)dy = 3. Solve for y ´ f (x)dx + C if possible. 16 Techniques of Integration 16.1 Integrals you must know 1. 2. 3. 4. 5. 6. 7. 8. ´ du = u + C ´ ur du = ´ ´ a du = au + C 1 u ur+1 r+1 +C du = ln|u| + C eu du = eu + C ´ r r+1 u du = ur+1 + C ´ sin(u) du = cos(u) + C ´ cos(u) du = sin(u) + C 14 9. 10. 11. 12. 13. 14. 15. 16. 17. ´ sec2 (u) du = tan(u) + C ´ sec(u)tan(u) du = sec(u) + C ´ tan(u) du = ln|cos(u)| + C ´ √1 1u2 ´ csc2 (u) du = cot(u) + C ´ csc(u)cot(u) du = csc(u) + C ´ cot(u) du = ln|sin(u)| + C ´ 1 1+u2 ´ du = sin−1 (u) + C du = tan−1 (u) + C √1 u u2 1 du = sec−1 (u) + C 16.2 U-substitution The purpose of a u-substitution is to make a dicult integral look like one of the integrals above. 16.3 Inverse chain rule theorem ˆ f (g(x))g 0(x) = F (g(x)) + C This theorem can be used to solve u-substitution integrals like ´ √ 2x 19x2 dx 16.4 Integration by parts ˆ ˆ ˆ 0 0 f (x)g(x)|ba f (x)g (x) dx = f (x)g(x) b f (x)g (x)dx = a ˆ f 0 (x)g(x) dx b f 0 (x)g(x)dx a 17 The Denite Integral 17.1 Denition ˆ b f (x) dx = a lim max∆xk →0 15 n X k=1 f (xk n )∆xk . 17.2 Fundamental theorems • • • • • ´b f (x) dx = F (b)F (a) ´ d f (x) = f (x) dx ´ d f (x)dx = f (x) + C dx ´x f (t)dt = F (x) where F (a) = 0 a ´x d f (t)dt = f (x) dx a a 17.3 Approximations to the denite integral (n will be given) 17.3.1 Riemann sums using midpoints ˆ 17.3.2 b a f (x)dx ≈ ba [y1 + y2 + ... + yn ] n Trapezoids ˆ b a f (x)dx ≈ ba [f (a) + 2f (x1 ) + 2f (x2 ) + ... + f (b)] 2n 17.4 Denite integral as area • ´b • ´d f (x)dx =area between f (x) and the x-axis on [a, b] if f (x) ≥ 0 on [a, b] ´ b • a f (x)dx =area between f (x) and the x-axis on [a, b] if f (x) ≤ 0 on [a, b] a u(y)dy =area between u(y) and the y-axis on [c, d] if u(y) ≥ 0 on [c, d] ´ d • c u(y)dy =area between u(y) and the y-axis on [c, d] if u(y) ≤ 0 on [c, d] c 18 Applications of the Denite Integral 18.1 Motion along a line • Go from a(t) → v(t) → x(t) • Remember, the given conditions will determine the values of the constants generated by integrating. by integration. = ´ t=b • Displacement • Distance traveled is the sum of the distances traveled right and left. t=a position at time= a, v(t)dt at every value of time where the distanced traveled on each time interval. 16 v(t) = 0, Evaluate the and at time= b. Add up 18.2 Mean value (average value of a function) on [a, b] ´b a fav = f (x)dx ba 18.3 Area between two curves When nding the area between two curves, either axis can be used for orientation. the variable of integration • X-axis: R= • Y-axis: R= ´b a ´d c must However, be the same as the axis of orientation. [f (x)g(x)] dx [u(y)v(y)] dy 18.4 Volume of a solid of revolution 18.4.1 Around an axis The axis of revolution is determined in the problem. However, either axis can be used for orientation. must If the axis of orientation is dierent from the axis of revolution, the volume be found using shells. In general, it is simplest to use disks/washers for volumes of revolution around the x-axis, and shells for volumes of revolution around the y-axis. • • Disks with one curve (axis of revolution=axis of orientation=variable of integration): b x − axis : V = π ˆ d y − axis : V = π ˆ [f (x)]2 dx a [u(y)]2 dy c Washers with two curves (axis of revolution=axis of orientation=variable of integration) 18.4.2 b x − axis : V = π ˆ y − axis : V = π ˆ a d c [f (x)]2 [g(x)]2 dx [u(y)]2 [v(y)]2 dy Around a line If the line is parallel to the x-axis, then your variable of integration must be parallel to the y-axis, then your variable of integration must be V =π ˆ a b R2 r 2 dr Both radii must be in terms of the appropriate variable. 17 y. x. If the line is In either case, remember: 18.4.3 Volumes of known cross sections If the cross-sections are perpendicular to the x-axis, then your variable of integration is If the cross-sections are perpendicular to the y-axis, then your variable of integration is In either case, remember: V = V = ˆ b A(x)dx a ˆ d A(y)dy c 18 x. y.