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# algebra 1

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The equation x2 – 1x – 90 = 0 has solutions {a, b}. What is a + b?

Mar 30, 2020

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First you factor the equation into $$(x-10)(x+9) = 0$$.

So you're solutions are $$10$$ and $$-9$$. The sum of 10 and -9 is $$1$$.

Mar 30, 2020

#1
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By vietas formulas:

a + b = -(-1)/1 = 1/1 = 1

Vietas formulas state:

Given a quadratic(it can be any polynomial, I'd recommend searching up vieta's formulas)

$$ax^2+bx+c = 0$$

and roots: x1, x2

x1 + x2 = $$\frac{-b}a$$

x1*x$$\frac ca$$

Mar 30, 2020
edited by jfan17  Mar 30, 2020
#2
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First you factor the equation into $$(x-10)(x+9) = 0$$.
So you're solutions are $$10$$ and $$-9$$. The sum of 10 and -9 is $$1$$.