Graphing Linear Inequalities
Unit 5
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
– He wants to save at least $50 to buy a Wii game.
– He doesn’t really like working at QT because . . . well,
it’s work. It pays better than babysitting though.
– He would rather babysit to earn money because he
can watch TV and text his friends. He just wished he
got paid more to do basically nothing.
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
– What are the possible hours that he could work to
get the money?
– First the equation Ax + By = C or in this case 10Q +
5B = 50.
– Wait a minute. The equals means that Stephen
only wants to make $50. The original question
said that he wanted to make AT LEAST $50. That’s
different.
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
• That involved an inequality.
• So our problem is not 10Q + 5B = 50, it’s
10Q + 5B ≥ 50
• Now we need to graph it. Remember, we are going
to solve this like it is an equation so that we can solve
for Q (like x) and B (like y).
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
10Q + 5B = 50
10Q + 5(0) = 50
10Q + 0 = 50
10Q = 50
10
10
Q=5
The B is now a zero so we can find
the x-intercept.
5 times 0 is zero. Get rid of it.
Divide both sides by 10.
The x-intercept is (5,0)
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
10Q + 5B = 50
10 (0) + 5B = 50
0 + 5B = 50
5B = 50
5
5
B = 10
The Q is now a zero so we can find
the y-intercept.
10 times 0 is zero. Get rid of it.
Divide both sides by 5.
The y-intercept is (0, 10)
Stephen makes $10 per hour working at QT
and $5 per hour babysitting.
Get the Coach book
from under your desk.
• Turn to p. 189.
Test Wednesday
Know the Slope Formula and the Slope Intercept
Form.
Know the variables and meanings of slope and yintercept of the Slope Intercept Form,
y = mx + b.
Know how to solve the slope from the Slope
Formula m = y2 – y1
x2 – x1
HW – Due Th/Fri
• Worktext p. 405 & 406