SOLUTION: Solve {{{7x^2-9=16}}} using the quadratic formula, writing the answer as a simplified radical expression.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Solve {{{7x^2-9=16}}} using the quadratic formula, writing the answer as a simplified radical expression.       Log On


   

Question 48976: Solve 7x%5E2-9=16 using the quadratic formula, writing the answer as a simplified radical expression.
Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
7x%5E2-9=16[Set the equation equal to zero by subtracting 16 from both sides]
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7x%5E2+-+25+=+0
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7x%5E2+%2B+0x+-+25+=+0 [Add the term (0x) to make it easier to work with]
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7x%5E2+%2B+0x+-+25+=+0
a=7
b=0
c=-25
x+=++%28-0+%2B-+sqrt%28+0%5E2-%284%29%287%29%28-25%29+%29%29%2F%28%282%29%287%29%29+ [Plug-in the values]

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x+=+%28-0+%2B-+sqrt%28+-%284%29%287%29%28-25%29+%29%29%2F%28%2814%29%29%29+ [Simplify]
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x+=+%28-0+%2B-+sqrt%28+700%29+%29%29%2F%28%2814%29%29%29+
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x+=+%28-0+%2B-+26.4575%29%2F%28%2814%29%29%29%29+
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x = +26.4575/14 = 1.8898
x = -26.4747/14 = -1.8898