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3 years ago

One root of the equation x2+6x+q=0 is twice the other root. find q and the roots.

1 answer:

8 0

Suppose one of the roots is a the second is 2a. The factors will be:
(x-a) and (x-2a)
thus
(x-a)(x-2a)=x^2+6x+q
x^2-xa-2ax+2a^2=x^2+6x+q
taking corresponding terms we shall have:
-2ax=6x
solving for a we get
-2a=6
thus
a=-3
but
q=2a^2
substituting the value of a we get:
q=2(-3)^2
q=2*9
q=18

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