Questions on Algebra: Introduction to vectors, addition and scaling answered by real tutors!

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Question 101988: How do you figure out this Factor:
5x^2 + 5x – 30: How do you figure out this Factor:
5x^2 + 5x – 30
Answer by mathemanic(13) About Me  (Show Source):
You can put this solution on YOUR website!
5x^2 + 5x – 30
Suppose that two numbers: a and b satisfy conditions as such:
a * b = 5 * -30
a + b = 5
Therefore a = 15 and b = -10.
To factorize the quadratic equation above,
((5x + a) * (5x + b)) / 5
((5x + 15) * (5x - 10)) / 5
(5x + 15) * (x - 2)
To find the solution,
(5x + 15) * (x - 2) = 0
so either (5x + 15) = 0 or (x - 2) = 0
Therefore the solutions for x is either x[1] = -3 or x[2] = 2 .
Cheers.