Equation of tagent line when x is given, but not Y.

[BrianHare]

Homework Statement

Find the equation of the line tangent to y=(x²+3x)² (2x-2)³, when x=8

Homework Equations

The Attempt at a Solution

dy/dx = 56x^6+144x^5-240x^4-320x^3+504x^2-144x...or...8x(x+3)(x+2)(7x-3)(x-1)²
dy/dx (8) = 18282880
y(x) = 21249536

Equation of tangent line at x=8;
y= 18282880x - 125013504

The problem is that this is a calc 1 question, 2 months in. There seems to be an odd space between the (x²+3x)² and (2x-2)³. I think the teacher might forgot to put a + or a - in the problem. What do you all think?

If I use a minus, I get a perfect 5000 for y(8). Making the end equation
y=2168x-12344.

Am I doing something wrong?

 

[Gib Z]

If that's how the question was given, that's how it should be answered. Its not your job to try guess their typos =]