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Can someone help me ASAP please

Can someone help me ASAP please-example-1

1 Answer

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Well, it's a quadratic, so it has to have 2 roots. 'Roots' meaning when its velocity is 0 or in this case, the ball hits the ground. So, let's just throw this into the quadratic equation. Remember, the quadratic equation is:

x = (-b + √(b^2-4ac) )/(2a)
and

x = (-b - √(b^2-4ac) )/(2a)

To plug values in, let's first rearrange the equation, so it's easier to plug in:

h = -5t^2-10t+65

Plug in (a = -5, b = -10, c = 65) and since we are solving for t, not x:

0 = -5t^2-10t+65

t = (10+ √((-10)^2-4(-5)(65)) )/(2(-5))
and

t = (10+ √((-10)^2-4(-5)(65)) )/(2(-5))

Solve:

t = (10+ √(100+1300) )/(-10) = (10+ √(1400) )/(-10)
and

t = (10- √(100+1300) )/(-10) = (10- √(1400) )/(-10)

Simplify:

t = (10+37.42)/(-10) =-4.742
and

t = (10-37.42)/(-10) = 2.742

Since time cannot be negative, your answer is the ball takes 2.742 seconds to hit the ground.
User Hana Bzh
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