SOLUTION: solve the equation by completing the square: {{{4x^2+40x+280=0}}}

Question 216874: solve the equation by completing the square:
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
solve the equation by completing the square: 4x^2 + 40x + 280 = 0
4x^2 + 40x + ___ = -280
:
Divide both sides by 4
x^2 + 10x + ____ = -70
:
Find the value of the 3rd term that completes the square
using the coefficient of x: (10/2)^2 = 25
x^2 + 10x + 25 = -70 + 25
:
x^2 + 10x + 25 = -45
:
Which is:
(x + 5)^2 = -45
:
Find the square root of both sides
x + 5 = +/-
:
x + 5 = +/-
:
Extract the square root of -1 and 9
x + 5 = +/-
:
Two solutions

and

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