vinayanand wrote:

I used two different methods to solve an equation and I'm getting different answers. I'm not sure where am I going wrong.

Method 1 - Solving for x

\(x^2-16=x-4\)

\(x^2-x-12=0\)

\((x-4)(x+3)=0\)

\(x=4, -3\)

Method 2 - Solving for x

\(x^2-16=x-4\)

\(x^2-4^2=x-4\)

\((x+4)(x-4)=x-4\)

\((x+4)=\frac{(x-4)}{(x-4)}\)

\((x+4)=1\)

\(x=-3\)

It looks like something is wrong with method 2. Also in method 2 x cannot be 4 else the denominator will be 0.

Can someone tell me what am I doing wrong in method 2.

Thank you

Check out this post for an explanation on when you can/cannot divide by a variable:

in-which-one-of-the-following-choices-must-p-be-greater-than-127621.html#p1048624 _________________

Karishma

Veritas Prep | GMAT Instructor

My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews