SOLUTION: An astronaut on the moon tosses a ball upwards; when will the ball initially be 35 feet above the lunar surface if the ball's height (feet) follows: h(t) = -2.6t^2 + 32.1t + 5.5, a

Question 147563: An astronaut on the moon tosses a ball upwards; when will the ball initially be 35 feet above the lunar surface if the ball's height (feet) follows: h(t) = -2.6t^2 + 32.1t + 5.5, and t is in seconds from release?
a. 1 second
b. 2 seconds
c. .5 seconds
d. 13.2 seconds
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Start with the given equation.

Plug in

Multiply both sides by 10 to clear out the decimals.

Distribute and multiply.

Subtract 350 from both sides.

Combine like terms.

Let's use the quadratic formula to solve for t

Start with the quadratic formula

Plug in , , and

Square to get .

Multiply to get

Subtract from to get

Multiply and to get .

Take the square root of to get .

or Break up the expression.

or Combine like terms.

or Simplify.

So our answers are or

where the second answer approximates

So when the ball is initially at 35 feet, the time is .
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