Question

Find the square of:
1. (5x-4y-9z) ^2

Answer 1

$\huge{\underline{\underline{\mathfrak{\orange{AnSwEr}}}}}$

By using identity

$(a + b + c)^{2} = a {}^{2} + b {}^{2} + c {}^{2} + 2ab + 2bc + 2ca$

$\rule{190}2$

$\large\blue{Solution}$

$\sf=>(5x){}^{2}+ ( - 4y)^{2} + ( - 3z) ^{2} + 2(5x \times - 4y) + 2( - 4y \times - 3z) + 2( - 3z \times5x)$

$\sf=>25 {x}^{2} - 16y {}^{2} - 81z {}^{2} - 40xy + 72yz - 90zx$