Page 136 - Algebra

The maximum height is h(t) = 120t – 8t2
h(t) = 120(15) – 8(15)2 22
h(t) = 900 – 450 h(t) = 450 meters
8. When the ball hits the ground the height will be 0 h(t) = 120t – 8t2
0 = 120t – 8t2 120t = 8t2
8t = 120
t = 15 seconds
9. x + y – 7 = 0
Write it in term of y y = 7– x
Putitiny=x2 +2x–3 7 – x = x2 + 2x – 3
x2 + 2x – 3 – 7 + x = 0 x2 +3x–10=0
x2 +5x–2x–10=0
x(x + 5) – 2(x + 5) = 0
(x – 2) (x + 5) = 0
x = 2 and x = –5
When x = 2, y = 5
So, the solution is (2, 5)
When x = –5, y = 12
So, the solution is (–5, 12)
10. The solution of system of equations is the point where all the three equations intersect. There are two points where the three equations meet.
The two points are as follows:
Page 135 of 177
Algebra I & II