How do you solve x(x+6)=-15 using the quadratic formula?

1 Answer
Jack Oneill
Oct 25, 2017

No real solutions, x>0

Explanation:

Expand boiii

x(x+6)

x*x = x^2

x * 6 = 6x

We have -15, bring that over to make + 15

so the equation is x^2 + 6x + 15 = 0

collect terms for the quadratic formula (-b +- sqrt(b^2 - 4(a)(c)))/(2a)
a is the number in front of x^2
b is the number in front of x
c is the number without an x, poor lonely number

a = 1
b = 6
c = 15
remember minuses matter, however there are none in this question.

so plug it in
( -6 +- sqrt(6^2 - 4(1)(15)))/(2(1))

put into your calculator as is, i'd suggest one from here: https://goo.gl/JtHwiA they are brilliant. (Casio 991ex)

This leaves a negative number in your square root, which means imaginary numbers.. No real solution is obtainable

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