Question

Expand ( -2x + 5y – 3z)^2 using suitable identity

Answer 1

ANSWER:-

$( - 2x + 5y - {3z})^{2} is \: of \: the \: form \: (a + b + {c})^{2}$

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

$= > where \: a = - 2x \: b = 5y \: c = - 3z$

$∴( - 2x + 5y - {3z})^{2} = ( { - 2x})^{2} + ( {5y})^{2} + ( {3z})^{2} + 2( - 2x)(5y) + 2 (5y)( - 3z) + 2( - 3z)( - 2x)$

$= > 4 {x}^{2} + 25 {y}^{2} + 9 {z}^{2} - 20xy - 30yz + 12zx$

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Answer 2

$\huge{\underline{\mathfrak{\pink{Question }}}}$

• Expand ( -2x + 5y – 3z)^2 using suitable identity

$\huge{\underline{\mathfrak{\pink{Answer}}}}$

( -2x + 5y - 3z)² is of the form (a + b + c)²

( a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ca

where,

-› a = -2x

-› b = 5y

-› c = -3z

∴ (−2x+5y−3z) ² =(−2x) ² +(5y) ² +(−3z)² + 2(−2x)(5y)+2(5y)(−3z)+2(−3z)(−2x)

$= 4 {x}^{2} +25y {}^{2} + 9 {z}^{2} - 20xy - 30xy + 12zx$