# Sum of two functions (graphs)

• Jul 18th 2011, 05:44 PM
jbwtucker
Sum of two functions (graphs)
This is not from a test; I'm not cheating. It's from a sample test. I take the actual test on Friday, and I haven't seen those questions.
• Jul 18th 2011, 06:04 PM
pickslides
Re: Sum of two functions (graphs)
I think option A is a pretty good answer but what is your guess? How did you arrive at it?
• Jul 18th 2011, 06:06 PM
Also sprach Zarathustra
Re: Sum of two functions (graphs)
Quote:

Originally Posted by jbwtucker
This is not from a test; I'm not cheating. It's from a sample test. I take the actual test on Friday, and I haven't seen those questions.

g(x)=ax^2 (a>0)

f(x)=mx (m>0)

So, what can you tell me?
• Jul 18th 2011, 06:26 PM
jbwtucker
Re: Sum of two functions (graphs)
Right. And they look like parent functions, so I'm guessing g(x)=x^2 and f(x)=x, or something close to it. So adding them together yields x^2 + x, which is still a parabola, just a steeper one.

As we head towards negative numbers, the value of y should shift down... until |x| is a big enough number that squaring it outweighs adding a negative x-value and sends it back into quadrant 2.

Which means it's A.

Thanks!