Question 1019a

Definite Integrals: Areas and Volumes

Question

The curve C{C} has equation
y=4x3+8x5.y=4 x^3 + 8 x - 5.
(i)
C{C} crosses the x-axis{x\textrm{-axis}} at the point with coordinates (a,0).{(a,0).} Find the value of a{a} correct to 3{3} decimal places.
[1]
(ii)
You are given that b>a.{b>a.}

The region P{P} is bounded by C,{C,} the x-axis{x\textrm{-axis}} and the lines x=1{x=-1} and x=0.{x=0.} The region Q{Q} is bounded by C,{C,} the line x=b{x=b} and part of the the x-axis{x\textrm{-axis}} between x=a{x=a} and x=b.{x=b.}

Given that the area of Q{Q} is 8{8} times the area of P,{P,} find the value of b{b} correct to 3{3} decimal places.

[4]

Answer