SOLUTION: solve by completing the square? x^2+4x-5=0

Algebra.Com
Question 29170: solve by completing the square?
x^2+4x-5=0

Answer by sdmmadam@yahoo.com(530)   (Show Source): You can put this solution on YOUR website!
solve by completing the square?
x^2+4x-5=0 ----(*)
x^2+4x =5
(x)^2+2X(x)X(2) =5
(LHS resembles (a)^2+2ab where a=x and b=2. And we require (b)^2 to complete the square. So we add (b)^2 = 2^2 = 4 to both the sides)
(x)^2+2X(x)X(2)+4 =5+4
(x+2)^2 =9
Taking the square root,
(x+2) = + or minus 3
(x+2) = 3 or (x+2) = -3
That is x= 3-2 or x = -3-2
x=1 and x=-5
Ans: x=1 and x=-5
Verificaiton:x=1 in (*)
LHS= x^2+4x-5 = (1)^2+4X(1)-5 = 1+4-5 = 0 =RHS
x=-5 in (*)
LHS= x^2+4x-5 = (-5)^2+4X(-5)-5 = 25+-20-5 = 25-25=0 =RHS
Therefore our values are correct.

RELATED QUESTIONS

Solve by completing the square:... (answered by jim_thompson5910)
Solve by completing the square. x^2 + 4x - 5 =... (answered by asuar010)
Solve by completing the square... (answered by SandySharma,Edwin McCravy)
Solve by completing the square... (answered by madhujiithcharu@yahoo.co.in)
Solve: x^2 - 4x - 1=0 by completing the... (answered by jim_thompson5910)
Solve by completing the square: x^2-... (answered by edjones)
solve by completing the square.... (answered by mananth,Alan3354)
Solve by completing the square 3x^2 - 4x + 5 =... (answered by ptaylor)
solve by completing the square:... (answered by lynnlo)