Which quadratic equation has roots -2, 1/5
A. x^2+4x+4=0
B. 5x^2-9x-2=0
C.5x^2+9x-2=0
D.5x^2-11x+2=0

How do you find the roots of an equation?

Question

Which quadratic equation has roots -2, 1/5
A. x^2+4x+4=0
B. 5x^2-9x-2=0
C.5x^2+9x-2=0
D.5x^2-11x+2=0 

How do you find the roots of an equation?

anonymous · Answer

you find roots of an equation by factoring the given equation

anonymous · Answer

i still don't understand how they got 1/5 as a root. i have narrowed it down between c and b

lgbasallote · Answer

there is an easier way actually... since -2 and 1/5 are roots that means..

x = -2
x = 1/5

so...

(x + 2)(x - 1/5) is your polynomial now expand it

anonymous · Answer

ok, when you factor either c or b, you are left with two brackets...if you set each bracket = to zero and solve for x, you willl get the roots of the equation

lgbasallote · Answer

after you solve for that by FOIL/distributive..it seems you have to multiply every term by 5 to match your options

anonymous · Answer

i ended up getting c.

anonymous · Answer

in the problem, they give you roots of -2, and 1/5 ...those numbers are also what you get when you solve for x... x= -2 and x = 1/5 
so, now, that you know the roots, or what "x" is equal to, you could work backward..
 (x+2)(5x-1)  ...this factoring gives you roots of -2 & 1/5 and if you use the FOIL method to multiply (x+2)(5x-1), you will get "C" as the answer!

anonymous · Answer

Thank you guys for all your help!

anonymous · Answer

I truly am highly appreciative.

anonymous · Answer

youur welcome!  I'm glad I could help you better understand the stated problem! :)