SOLUTION: If a rock falls from a height of 20 meter on the planet Jupiter, its height H (in meters) after x seconds is approximately H(x)=20-13x^2 When is the height of the rock 15 meters

Question 661103: If a rock falls from a height of 20 meter on the planet Jupiter, its height H (in meters) after x seconds is approximately H(x)=20-13x^2
When is the height of the rock 15 meters?
I have already plugged 15 meters into the equation like this 15=20-13x^2
How do I solve for x?
Answer by lynnlo(4176) (Show Source): You can put this solution on YOUR website!
15=20-13x^2
(1)reverse the equality in 15=20-13x^2
it is the same as 20-13x^2=15
(2)isolate terms with x to the left side
subtract 20 from both sides
-13x^2=-5
(3)divide both sides by a constant to simplify
divide both sides by -13=x^2=5/3
(4)eliminate exponent on left side,take the square root both sides
answer====x=√5/13 OR x=-√5/13
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