Aladin_Baniel_GE-1B EXERCISE VI. A 43. The length of a rectangle is 3 inches greater than its width. Its area is 70 square inches. What are its dimensions? Step 1: Given a rectangle with a length 3 inches greater than its width it has an area of 70 square inches Required: dimensions of the rectangle Step 2: Assign variables Let x = width of the rectangle x + 3 = length of the rectangle x+3 x Step 3: Write an equation Area of rectangle = (length)(width) 70 = (x + 3)(x) Step 4: Solve 70 = (๐ฅ + 3)(๐ฅ) 70 = ๐ฅ 2 + 3๐ฅ ๐ฅ 2 + 3๐ฅ − 70 = 0 (๐ฅ + 10)(๐ฅ − 7) = 0 ๐ฅ + 10 = 0 ๐ฅ − 7 = 0 ๐ฅ = −10 ๐ฅ = 7 Step 5: State the answer In this equation the answer cannot be negative therefore the length of the rectangle is 10 inches and the width is 7 inches. Step 6: Check (7)(7 + 3) = 70 (7)(10) = 70 70 = 70 ๏ Aladin_Baniel_GE-1B 44. The diagonal of a rectangle is 2 inches greater than its length and 9 inches greater than its width. Find the dimensions of the rectangle. Step 1: Given a rectangle with a diagonal 2 inches greater than length and 9 inches greater than width Required: dimensions of the rectangle Step 2: Assign variables Let x = diagonal of the rectangle x – 2 = length of the rectangle x – 9 = width of the rectangle x- 2 x x- 9 Step 3: write an equation ๐ฅ 2 = (๐ฅ − 2)2 + (๐ฅ − 9)2 Derived from Pythagorean Theorem Step 4: Solve ๐ฅ 2 = (๐ฅ − 2)2 + (๐ฅ − 9)2 ๐ฅ 2 = ๐ฅ 2 − 4๐ฅ + 4 + ๐ฅ 2 − 18๐ฅ + 81 ๐ฅ 2 = 2๐ฅ 2 − 22๐ฅ + 85 ๐ฅ 2 − 22๐ฅ + 85 = 0 (๐ฅ − 17)(๐ฅ − 5) = 0 ๐ฅ − 17 = 0 ๐ฅ−5=0 ๐ฅ = 17 ๐ฅ=5 ๐๐๐๐ ๐๐ ๐กโ๐ ๐๐๐๐ก๐๐๐๐๐ = ๐๐ค (15)(8) = 90 Step 5:State the answer In this equation, the sides of the rectangle should not be negative, therefore, the length of the rectangle is 15 inches and the width is 8 inches of which the diagonal is 17 inches. Step 6:Check 172 = 152 + 82 289 = 225 + 64 289 = 289 ๏ Aladin_Baniel_GE-1B 45. Find two consecutive positive integers whose product is 1332. Step: Given two consecutive integers product is 1332 Required: the two integers Step 2: Assign variables Let x = first integer x + 1 = second integer Step 3: Write an equation (x)(x + 1) = 1332 Step 4: Solve (๐ฅ)(๐ฅ + 1) = 1332 ๐ฅ 2 + ๐ฅ = 1332 2 ๐ฅ + ๐ฅ − 1332 = 0 (๐ฅ + 37)(๐ฅ − 36) = 0 ๐ฅ + 37 = 0 ๐ฅ − 36 = 0 ๐ฅ = −37 ๐ฅ = 36 Step 5: State the answer In this equation the answer should not be negative, therefore the first integer is 36 and the second integer is 37. Step 6: Check (36)(36 + 1) = 1332 (36)(37)=1332 ๏ Aladin_Baniel_GE-1B 47. Find two consecutive positive positive odd integers whose product is 783. Step 1: Given two consecutive odd integers their product is 783 Required: the integers Step 2: Assign variables Let x = first integer x + 2 = second integer Step 3: Write an equation (x)(x+2) = 783 Step 4: Solve (๐ฅ)(๐ฅ + 2) = 783 ๐ฅ 2 + 2๐ฅ = 783 2 ๐ฅ + 2๐ฅ − 783 = 0 (๐ฅ − 27)(๐ฅ + 29) = 0 ๐ฅ − 27 = 0 ๐ฅ + 29 = 0 ๐ฅ = 27 ๐ฅ = −29 Step 5: State the answer In this equation the answer cannot be negative, therefore the first integer is 27 and the second integer is 29. Step 6: Check (27)(27+2) = 783 (27)(29) = 783 783 = 783 ๏ Aladin_Baniel_GE-1B 48. One number is ten more than another. Their product is 299. What are the numbers? Step 1: Given two numbers the second number is ten more than the other their product is 299 Required: the numbers Step 2: Assign variables Let x = first number x + 10 = second number Step 3: Write an equation (x)(x+10) = 299 Step 4: Solve (๐ฅ)(๐ฅ + 10) = 299 ๐ฅ 2 + 10๐ฅ = 299 ๐ฅ 2 + 10๐ฅ − 299 = 0 (๐ฅ − 13)(๐ฅ + 23) = 0 ๐ฅ − 13 = 0 ๐ฅ + 23 = 0 ๐ฅ = 13 ๐ฅ = −23 Step 5: State the answer In this equation the answer cannot be negative, therefore the first number 13 and the second number is23 Step 6: Check (13)(13+10) = 299 (13)(23) = 299 299 = 299 ๏ Aladin_Baniel_GE-1B 50. A tray with square base and a volume of 648 cubic inches is to be constructed from a square sheet of tin by cutting 2-inch squares from the corners and bending up the sides. What size of sheet of tin should be used? Step 1: Given a tray with a volume of 648 is made from a square sheet that is cut 2-inch square from its edge Required: size of the square sheet Step 2: Assign variables Let x = side of the square base of the tray x + 4 = side of the square sheet 2 x 2 2 2 x x 2 2 2 x X Volume = 648cubic inch 2 inch 2 Step 3: Write an equation (x)(x)(2) = 648 Step 4: Solve (๐ฅ)(๐ฅ)(2) = 648 2๐ฅ 2 = 648 2๐ฅ 2 2 = Side of square sheet = 18 + 4 = 22 inch 648 2 ๐ฅ = √324 ๐ฅ = 18 Step 5: State the answer Therefore the size of the square sheet should be 22x22 suare inch. Step 6: Check (18)(18)(2) = 648 648 = 648 ๏ Aladin_Baniel_GE-1B 51. A rectangular sheet of cardboard is twice as long as it is wide. An open box having a capacity of 168 cubic inches is made by cutting 3 inch squares from the cornes and banding up the sides and ends. Find the dimensions of the cardboard. Step 1: Given a rectangular sheet of card board having a length of twice as long as its width its cut 3 inch squares from its corners making an open box that has a volume of 168 cubic inch Required: dimensions of the rectangular sheet of cardboard Step 2: Assign variables Let x = width of the rectangular sheet of cardboard 2x = length of the rectangular sheet of cardboard x – 6 = width of the box 2x – 6= length of the box 3 2x 3 3 3 x 3 2x-6 3 3 x-6 3inch 3 Volume=168 cubic inch Step 3: Write an equation (2x – 6)(x – 6)(3) = 168 Step 4: Solve (2๐ฅ − 6)(๐ฅ − 6)(3) = 168 (2๐ฅ − 6)(3๐ฅ − 18) = 168 2 6๐ฅ − 36๐ฅ − 18๐ฅ + 108 = 168 6๐ฅ 2 − 54๐ฅ + 108 − 168 = 0 6๐ฅ 2 − 54๐ฅ − 60 = 0 (6๐ฅ − 60)(๐ฅ + 1) = 0 6๐ฅ − 60 = 0 ๐ฅ+1=0 6๐ฅ 60 =6 ๐ฅ = −1 6 ๐ฅ = 10 Step 5: State the answer In this equation the answer cannot be negative, therefore the width of the rectangular sheet is 10inches and the length is 20inches and its area is 200-square inch. Step 6: Check (10 – 6)(20 – 6)(3)=168 (4)(14)(3)=168 168 = 168 ๏ Aladin_Baniel_GE-1B 52. A party of fishermen rented a boat for $240. Two of the men had to withdraw from the party and, as a result, the share of each of the others was increased by $10. How many were in the original party? Step 1: Given a group of fishermen rent a boat for $240 if two of them leave the group each payment will increase by $10 Required: number of fishermen in the original group Step 2: Assign variables Let x = number of original group of fishermen Step 3: Write an equation 240 240 = − 10 ๐ฅ ๐ฅ−2 Step 4: Solve 240 ๐ฅ 240 ๐ฅ 240 ๐ฅ 240 = ๐ฅ−2 − 10 = = 240−10๐ฅ+20 ๐ฅ−2 260−10๐ฅ ๐ฅ−2 240๐ฅ − 480 = −10๐ฅ 2 10๐ฅ 2 + 240๐ฅ − 260๐ฅ − 480 = 0 10๐ฅ 2 + 20๐ฅ − 480 = 0 (5๐ฅ + 30)(2๐ฅ − 16) = 0 5๐ฅ + 30 = 0 2๐ฅ − 16 = 0 5๐ฅ −30 2๐ฅ 16 = 5 = 2 5 2 ๐ฅ = −6 ๐ฅ=8 Step 5: State the answer In this equation the answer cannot be negative, therefore the number of the original group of fishermen is 8. Step 6: Check 240 Payment of original group = 8 = 30 240 When two of the men left = 6 = 40 40 – 30 = 10 ๏ Aladin_Baniel_GE-1B 53. A man drove 156 miles at a constant rate. If he had driven 5 miles per hour faster he would have made the trip in 12 minutes less time. How fast did he drive? Step 1: Given A man drove 156 miles at a constant rate He had driven 5 miles per hour faster He would have made the trip in 12 minutes less time Required: How fast did he drive? Step 2: Assign values Let 156 miles=distance x mph=rate 156/x hours=time Let 156 miles=distance x+5 mph=rate 156 miles/x+5 mph=time Step 3: Write an equation Note that 12 minutes is equal to 1/5 hour… 156/x-(156/(x+5))=1/5 hour Step 4:Solve 156 ๐ฅ 156 1 − (๐ฅ+5) = 5 โ๐๐ข๐ ๐ฅ(๐ฅ+5) 156(๐ฅ + 5) − 156 = 5 156 ∗ 5 ∗ 5 = ๐ฅ 2 + 5๐ฅ ๐ฅ 2 + 5๐ฅ − 3900 = 0 (๐ฅ − 60)(๐ฅ + 65) = 0 ๐ฅ − 60 = 0 ๐ฅ + 65 = 0 ๐ฅ = 60 ๐ฅ = −65 Step 5:State the answer In this equation the answer cannot be negative, therefore the man drove at the speed of 60 mph Step 6:Check 156 ๐ฅ 156 60 156 1 − (๐ฅ+5) = 5 โ๐๐ข๐ − 156 60+5 = 1 5 156(65)−156(60) (60)(65) 1 5 1 =5๏ 1 =5 Aladin_Baniel_GE-1B 54. An airplane flying north at the rate of 240 miles per hour passed over a flying field at noon. A second plane flying east at 200 miles per hour passed over the same field 5 minutes later. When were they 250 miles apart? Step 1: Given an airplane flying north at the rate of 240mph passed a over a flying field a second airplane flying east at the rate of 200mph passed over the same field 5 mins later Required: time in which they were 250 miles apart Step 2: Assign variables and values Let t= no. of minutes after 12 noon when the two planes were 250 miles apart 240/60 t=4t= no. of miles that the first airplane travel 200/60 t=3.33(t-5) = no. of miles that the second airplane travel Step 3: Write an equation 200 (4๐ก)2 + ( 60 (๐ก − 5))2 = 2502 Step 4: Solve 200 2 (4๐ก)2 + ( 60 (๐ก − 5)) = 2502 16๐ก 2 + 11.1๐ก 2 − 111.1๐ก + 277.79 = 2502 27.1๐ก 2 − 111.1๐ก − 62 222.2 = 0 Solve for t using the quadratic equation ๐ก= ๐ก= −๐±√๐ 2 −4๐๐ 2๐ −(−111.1)±√(−111.1)2 −4(27.1)(62 222.2) ๐ก = 50 2(27.1) ๐ก = −45.9 Step 5: State the answer Therefore the planes were 250 miles apart at 12:50 pm and 11:14 am. Step 6: Check 2 (200)2 + (3.3333333(45)) = (250)2 40000 + 22500 = 62500 62500 = 62500 ๏