Factoring x2+8x-15=0?

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Factor please! X=? and other X=
Update : its X(squared)
X^2+8x-15=0
Update 2: NEGITIVE X SQUARED. PLUS EIGHT X. MINUS FIFTEEN. EQUALS ZERO
Best Answer
since multiplication is commutative x2 is the same as 2x

2x + 8x - 15 = 0

10x - 15 = 0

10x = 15

x = 15/10 = 3/2. <==== Solution

EDIT: 2300 hours. Thursday, Oct. 20, 2011

Given: x² + 8x - 15 = 0

Not factorable, so use completing the square to solve.

x² + 8x + ☺ = ☺ + 15

☺ = (8/2)² = 16

x² + 8x + 16 = 16 + 15

(x + 4)² = 31

Take ±√ of both sides

x + 4 = ±√31

x = ±√31 - 4 <==== Solution

Reference: http://www.wolframalpha.com/input/?i=x%C...

EDIT: I just noticed you had -x² + 8x - 15 = 0

divide or multiply through by a -1.

x² - 8x + 15 = 0

Find two factors of 15 that sum to -8.

Those factors are -3 and -5.

(x - 3)(x - 5) = 0

x - 3 = 0 or x - 5 = 0

x = 3 or x = 5. <==== Solution

Source:

Math Professor ☺
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Other Answers (2)

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  • Zack R answered 3 years ago
    I do not think that this equation is factor able. I might be wrong but i think that there are no real solutions.
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  • ZX Neptunium XZ answered 3 years ago
    first learn to write the equation properly!

    its 2x + 8x - 15 = 0

    Source(s):

    where probably doing your homework for you so why not atleast ask it correctly?
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