Question

Expand: ${(7x+8y)}^3$

Answer 1

Given expression $(7x+8y{)}^3$

As we know that $(a+b{)}^3=a^3+3a^{2}b+3a{b}^2+b^3$
Substitute $a=7x,b=8x$ in above equation, we get
$(7x+8y{)}^3={\left(7x\right)}^3+{\left(8y\right)}^3+3{\left(7x\right)}^2\left(8y\right)+3\left(7x\right){\left(8y\right)}^2$
$=343x^3+256y^3+1176x^{2}y+1344x{y}^2$

$\therefore (7x+8y{)}^3=343x^3+256y^3+1176x^{2}y+1344x{y}^2$