Algebra 2 - Using QUADRATIC FORMULA (someone didn't do it for me correctly)

Algebra
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Solve each equation by using the Quadratic Formula.

1. 4x^2 - 9 = -7x - 4 (Wasn't sure about this one)

May 10th, 2015

4x^2 - 9 = -7x - 4

4x^2 + 7x - 9 + 4 = 0

4x^2 + 7x - 5 = 0


May 10th, 2015

4x^2 - 9 = -7x - 4

4x^2 + 7x - 9 + 4 = 0

4x^2 + 7x - 5 = 0

Factoring is useful only for those quadratic equations which have whole numbers. When you encounter quadratic equations that can not be easily factored out, use the quadratic formula to find the value of x by using the following formula.

x = (-b +(or) - root b^2 - 4ac)/2a

Here a = 4,      b = 7      and c = -5

x = [-7 + or - root 7^2 - 4*4*(-5)] / 2*4

   = [-7 + or - root (49 + 80)] / 8

    = (-7+ or - root 129) / 8

    = (-7 + 11.36) / 8          or        (-7 - 11.36) /8

   = 4.36 / 8                       or        -18.36 / 8

Therefore      x  = 0.55      or      x = - 2.29

May 10th, 2015

Thank you for the help!

May 10th, 2015

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