What is f(x) = int (x-1)^2+3x dxf(x)=(x1)2+3xdx if f(3)=2 f(3)=2?

1 Answer
Nov 19, 2016

Simply expand (x- 1)^2(x1)2 and then integrate using the rule intx^n(dx) = x^(n + 1)/(n + 1) + Cxn(dx)=xn+1n+1+C.

f(x) = intx^2 - 2x + 1 + 3xdxf(x)=x22x+1+3xdx

f(x) = intx^2 - x + 1dxf(x)=x2x+1dx

f(x) = 2/3x^3 - 1/2x^2 + x + Cf(x)=23x312x2+x+C

We can solve for CC now.

When x = 3x=3, y = 2y=2:

2 = 2/3(3)^3 - 1/2(3)^2 + 3 + C2=23(3)312(3)2+3+C

2 = 18 - 9/2 + 3 + C

-19 + 9/2= C

-29/2 = C

Hence, f(x) = 2/3x^3 - 1/2x^2 + x - 29/2.

Hopefully this helps!