Chapter 9.3, Problem 24Q

a.

To determine

To calculate after how many seconds lure reach at height of 12 ft .

Answer to Problem 24Q

  $t=\frac{1}{2}$

  $t=1$

Explanation of Solution

Given information:

Height

  $h=-16t^2+24t+4$

Calculation:

  $h=-16t^2+24t+4$

Put $h=12$

  $12=-16t^2+24t+4$

On solving,

  $2t^2-3t+1=0$

On solving,

  $2t^2-t-2t+1=0$

On solving,

  $t(2t-1)-1(2t+1)=0$

On solving,

  $(2t-1)(t-1)=0$

On solving,

  $(2t-1)=0$

  $(t-1)=0$

On solving,

  $t=\frac{1}{2}$

  $t=1$

b.

To determine

To calculate after how many seconds lure reach at water .

Answer to Problem 24Q

At $t=\frac{3}{2}$ seconds lure hit the water

Explanation of Solution

Given information:

Height

  $h=-16t^2+24t+4$

Height of water is 4 feet

Calculation:

  $h=-16t^2+24t+4$

Put $h=4$

  $4=-16t^2+24t+4$

On solving,

  $16t^2-24t=0$

On solving,

  $8t(2t-3)=0$

On solving,

  $t(2t-3)=0$

On solving,

  $t=0$

  $t=\frac{3}{2}$

At $t=\frac{3}{2}$ seconds lure hit the water