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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

Mid-Chapter Quiz

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Exercise 13 Page 132

Substitute h=0 into the function and solve for t.

7.5 sec.

To determine how much time a ball is in the air, we need to find out how much time it takes to reach a height of 0 feet. Let's substitute h=0 into our function and solve for t.

h = -16t^2+120t

h= 0

0 = -16t^2+120t

▼

Solve for t

Factor out -8t

0 = -8t(2t-15)

Use the Zero Product Property

lc-8t=0 & (I) 2t-15=0 & (II)

(I): .LHS /-8.=.RHS /-8.

lt=0 2t-15=0

(II): LHS+15=RHS+15

lt=0 2t=15

(II): .LHS /2.=.RHS /2.

lt=0 t=7.5

Since t=0 represents the starting time, we can say the ball is in the air for 7.5 sec.