# Thread: Two graphs have gradient functions dy/dx = 3x^2+3x+a and dy/dx = 3x^2-2x+1.

1. ## Two graphs have gradient functions dy/dx = 3x^2+3x+a and dy/dx = 3x^2-2x+1.

Hey, I am struggling and I need a help please !
I tried to do it but I am sure that's completly wrong ....

1. Two graphs have gradient functions dy/dx = 3x^2+3x+a and dy/dx = 3x^2-2x+1. The graphs cross at the point (1, a) and also at the point where x=-2.
Find the equations of the two graphs, and the value of a.

2. Originally Posted by frz17
Hey, I am struggling and I need a help please !
I tried to do it but I am sure that's completly wrong ....

1. Two graphs have gradient functions dy/dx = 3x^2+3x+a and dy/dx = 3x^2-2x+1. The graphs cross at the point (1, a) and also at the point where x=-2.
Find the equations of the two graphs, and the value of a.
First thing I would do is to integrate those to given functions:

f1(x) = $\displaystyle{\int {(3x^2+3x+a)} \ \ dx}$

f2(x) = $\displaystyle{\int {(3x^2-2x+1)} \ \ dx}$

Did you do that?

What did you get?