Problem Solving

If x-2/x-5=x, then what is the value of x^2-6x+10?

Answer is 8.

Please check my workings:-

x-2=x(x-5)
x-2=x^2-5x
x^2-5x-x+2
x^2-6x+2 (I understand how they got 8(difference btw 10 & 2.But,it confuses because the question is
asking for the value of x^2-6x+10 so how do I make the connection with x^2-6x+2?)

2)If z>0 and m/n =x-y/z, then what is the value of n/m?

My workings:-

m/n=xz-y/z
Since, the question is asking for n/m,I'll just flip the fractions. So, n/m=z/xz-y(that's the
correct answer).

What is the usage of "If z>0"? I still can get the answer without using it.

Please check my workings and correct me if I'm wrong. "Beat The GMAT" is my only teacher.

Thanks a lot, guys.

shanice wrote:If x-2/x-5=x, then what is the value of x^2-6x+10?



Please check my workings:-

x-2=x(x-5)
x-2=x^2-5x
x^2-5x-x+2
x^2-6x+2 (I understand how they got 8(difference btw 10 & 2.But,it confuses because the question is
asking for the value of x^2-6x+10 so how do I make the connection with x^2-6x+2?)

Look at the portion that I have marked in red. You lost the equality sign there.
It should have been x² - 6x + 2 = 0 or x² -6x = -2
Substitute the value of x² - 6x in the expression x² - 6x + 10
=> x² - 6x + 10 = -2 + 10 = 8

shanice wrote:
2)If z>0 and m/n =x-y/z, then what is the value of n/m?

My workings:-

m/n=xz-y/z
Since, the question is asking for n/m,I'll just flip the fractions. So, n/m=z/xz-y(that's the
correct answer).

What is the usage of "If z>0"? I still can get the answer without using it.

Not if z = 0, the value of y/z would be undefined then.

Got it.Thank you very much.

By the way, I noticed that your test date is on 20th August 2012. I wish you all the best for your exam.