What is #f(x) = int (3x+5)^3-x dx# if #f(1)=-5 #?

1 Answer
Jan 21, 2018

just integrate

Explanation:

#f(x) = int((3x+5)^3-x)dx#

#=> int(3x+5)^3dx - intxdx#

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

#=> -5 = 1/12(3+5)^4 - 1/2 + c#

find c place it back in equation 1

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