2. Polynomials
hard

Without finding the cubes, factorise

$(x-2 y)^{3}+(2 y-3 z)^{3}+(3 z-x)^{3}$

Option A
Option B
Option C
Option D

Solution

Let $x-2 y=a, 2 y-3 z=b$ and $3 z-c=x$

$\therefore \quad a+b+c=x-2 y+2 y-3 z+3 z-x=0$

$\Rightarrow \quad a^{3}+b^{3}+c^{3}=3 a b c$

Hence, $(x-2 y)^{3}+(2 y-3 z)^{3}+(3 z-x)^{3}$

$=3(x-2 y)(2 y-3 z)(3 z-x)$

Standard 9
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.