Exercise 50 Page 41

To solve the equation, apply the Zero Product Property.

After 5 seconds

Practice makes perfect

We are given an equation that represents the height h, in feet, of a tennis ball. h=80t-16t^2To find how long it takes for the tennis ball to hit the ground, we need to substitute 0 for h, since at the ground level the height is zero.

h=80t-16t^2

Substitute

h= 0

0=80t-16t^2

FactorOut

Factor out 16t

0=16t(5-t)

To solve this equation, we will apply the Zero Product Property.

0=16t(5-t)

ZeroProdProp

Use the Zero Product Property

lc16t=0 & (I) 5-t=0 & (II)

▼

(I), (II): Solve for t

DivEqn

(II): .LHS /16.=.RHS /16.

lct=0 & (I) 5-t=0 & (II)

SubEqn

(II): LHS-5=RHS-5

lct=0 & (I) - t=- 5 & (II)

DivEqn

(II): .LHS /(- 1).=.RHS /(- 1).

lct=0 & (I) t=5 & (II)

The solutions to the equation are 0 and 5. Since the height of the arrow is initially zero, the arrow hits the ground after 5 seconds.

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Exercises p.39-42

Exercise 50 Page 41

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