How do you solve using the completing the square method x^2+10x-4=0x2+10x4=0?

2 Answers
Aug 1, 2016

x=+-sqrt29-5x=±295

Explanation:

You can express your quadratic equation as:
x^2+10x-4=(x+a)^2+bx2+10x4=(x+a)2+b

(x+a)^2+b=x^2+2ax+a^2+b(x+a)2+b=x2+2ax+a2+b

You will find 2ax=10x2ax=10x hence a=5a=5
a^2+b=-4a2+b=4
5^2+b=-452+b=4
b=-29b=29

Now you have: (x+5)^2-29=0(x+5)229=0
(x+5)^2=29(x+5)2=29
(x+5)=+-sqrt29(x+5)=±29
thereforex=+-sqrt29-5

Aug 1, 2016

x= -5+-sqrt29

Explanation:

x^2+10x-4=0 or (x+5)^2 -25-4=0 or (x+5)^2=29 or (x+5)=+-sqrt29 or x= -5+-sqrt29[Ans]