The equation for height is .

The initial height of the discus when .

The value of is substitute in the equation, .

The discus hit the ground then .

The value of is substitute in the equation, .

Multiply each side by negative one.

The general quadratic expression form is .

In the above trinomial, .

Since is negative, the factors m and p have opposite signs.

So either m or p is negative, but not both.

Since is negative, the factor with the greater absolute value is also negative.

To determine , list the factors of , where one factor of each pair is negative and look for the pair of factors with a sum of .

The correct factors are .

Apply the pattern: .

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Group terms with common factors.

Factors the GCF from each group.

Notice that is common in both groups, so it becomes the GCF.

Apply distributive property: .

The factors form of equation is .

Apply zero product property: .

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Solve the first equation, .

Solve the second equation, .

Subtract 1 from each side.

Divide each side by 16.

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The value of t can not be expressed in negative sign, so the value of .

(a)The initial height of the discus is ,

(b)The discus hit the ground after .