Question

evaluate the following question number 11c)

Answer 1

[ (0.4)³ - (0.24)³ ] / [ (0.4)² + 0.4 * 0.24 +(0.24)² ]

We know that a³ - b³ = (a-b)(a² + ab + b²)

=[(0.4 - 0.24)( (0.4)² + 0.4 * 0.24 + (0.24)² )] / [ (0.4)² + 0.4 * 0.24 +(0.24)²]

Since denominator is already in form a² + ab + b², the second bracket in numerator and the denominator get cancelled.
So, we have a - b left

= 0.4 - 0.24
= 0.16

Answer 2

Given [ (0.4)^3 - (0.24)^3 ] / [ (0.4)^2 + 0.4 * 0.24 +(0.24)^2 ]

this is in the form of  { (a-b)(a^2+ab+b^2) }

= [(0.4 - 0.24)( (0.4)^2 + 0.4 * 0.24 + (0.24)^2 )] / [ (0.4)^2 + 0.4 * 0.24 +(0.24)^2]

= 0.4 - 0.24 ( remaining get canceled )

= 0.16 ....
hence solved

hope it's help u