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gsenviro eNotes educator| Certified Educator

I assume that you would help with solving the value of 'x' in the given equation, f(x)=0

x^2-9x-70 = 0

For solving this quadratic equation, lets calculate the roots of the equation, which are

x = [9`+-` sqrt(9^2  -4*1*(-70))]/(2*1) = [9`+- ` sqrt(81+280)]/2 = [9`+- ` 19]/2 = 14, -5

Thus x= 14 and x=-5 satisfies this equation.

Hope this helps.

nick-teal eNotes educator| Certified Educator

If you were supposed to factor this, we can separate x^2 - 9x - 70 into two chunks.

We want to find two numbers that multiply to 70, but subtract to -9.

A list of factors of 70 are: 2 * 35, 10 * 7, 5 * 14... etc.

5 - 14 = -9, so we can factor this problem into

f(x) = (x + 5)(x - 14)

This leaves us with solutions x = -5, x = 14.

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