Question

factorise 5(3x - 4y)² - 20(2x -y)²​

Answer 1

$\huge{ \: \mathcal{ \pink{ \star\:Solution : \rightarrow }} }$

$\sf {\blue{ 5(3x - 4y)^{2} - 20(2x - y) ^{2} }}$

$\sf {\blue{ = 5 \{(3x - 4y)^{2} - 4(2x - y) ^{2} \} }}$

$\sf {\blue{ = 5 \{(3x )^{2} + ( {4y)}^{2} - 2(3x)(4y)- 4((2x ) ^{2} + {y}^{2} - 2(2x)(y))\} }}$

${ \: \mathcal{ \pink{ \star\: Formula: \rightarrow }} }$

${ \: \mathbb{ \pink{ \boxed{\star\: (a - b)^{2} = {a}^{2} + {b}^{2} - 2ab }}} }$

$\sf {\blue{ = 5 \{9x ^{2} + 16y^{2} - 24xy- 4(4x^{2} + {y}^{2} - 4xy)\} }}$

$\sf {\blue{ = 5 \{9x ^{2} + 16y^{2} - 24xy- 16x^{2} - 4 {y}^{2} + 16xy)\} }}$

$\sf {\blue{ = 5 \{ - 7x ^{2} + 12y^{2} - 8xy \} }}$