A curve with equation y=f(x) passes through the point (1, 4/3). Given that f'(x) = x^3 + 2*x^0.5 + 8, find f(x).

We know that f'(x) = x^3 + 2*x^0.5 + 8, and we can integrate both sides. This gives us f(x) = (1/4)*x^4 + (4/3)x^(3/2) + 8x + c, remembering to add the constant of integration. Now, we are almost there, but we need to use the first bit of information from the question. The curve y=f(x) passes through (1, 4/3), so when x=1, y=4/3. This is the same as saying that when x=1, f(x)=4/3, i.e. f(1)=4/3. But we know that f(1)= (1/4)*1^4 + (4/3)1^(3/2) + 81 + c, from before (just put 1 instead of x), so setting this equal to 4/3 gives: 1/4 + 4/3 + 8 + c = 4/3, 1/4 + 8 + c = 0, 33/4 + c = 0, c = -33/4. So f(x) = (1/4)*x^4 + (4/3)x^(3/2) + 8x - 33/4.

GC
Answered by George C. Maths tutor

6801 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

y=e^2x-11e^x+24 Find the stationary point, nature of the stationary point, the x-intercepts and the y-intercept (calculator allowed)


Why is the derivative of 2^x not x*2^(x-1)?


differentiate y=8x^3 - 4*x^(1/2) + (3x^2 + 2)/x


(a) Express (1+4*sqrt(7))/(5+2*sqrt(7)) in the form a+b*sqrt(7), where a and b are integers. (b) Then solve the equation x*(9*sqrt(5)-2*sqrt(45))=sqrt(80).


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning