What is f(x) = int (3x+5)^3-x dxf(x)=∫(3x+5)3−xdx if f(1)=-5 f(1)=−5?

1 Answer
Sanjay VN
Jan 21, 2018

just integrate

Explanation:

f(x) = int((3x+5)^3-x)dxf(x)=∫((3x+5)3−x)dx

=> int(3x+5)^3dx - intxdx⇒∫(3x+5)3dx−∫xdx

=> f(x) = 1/12(3x+5)^4 - x^2/2 + c⇒f(x)=112(3x+5)4−x22+c- 1
where c is a constant
now placing x=1x=1 and f(1)=-5f(1)=−5

=> -5 = 1/12(3+5)^4 - 1/2 + c⇒−5=112(3+5)4−12+c

find c place it back in equation 1

you can find f(x)
hope u find it helpful :)

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