Question

maths legend please solve this
expand the following by using identities​

Answer 1

Answer:

4x² + 25y² + 9z² - 20xy - 30yz + 2xz

Step-by-step explanation:

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

(-2x + 5y -3z)² = (-2x)² + (5y)² + (-3z)² + 2[ {-2x}{5y} + {5y}{-3z} + {-2x}{-3z} ]

                       = 4x² +25y² + 9z² + 2[ -10xy -15yz + 6xz]

                       = 4x² + 25y² + 9z² - 20xy - 30yz + 12xz

I hope this helps you!

Answer 2

$\LARGE\mathfrak{answer}$

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

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

where $\large\green{a=2x}$ , $\large\orange{b=5y}$ , $\large\blue{c=-3z}$

∴ $\large{(-2x\:+\:5y\:-\:3z)²}$ = (-2x)² + (5y)² + (-3z)² + 2(-2x) (5y) + 2(5y) (-3z) + 2(-3z) (-2x)

= $\large\pink{4x²\:+\:25y²\:+\:9z²\:-\:20xy\:-\:30yz\:+\:12zx}$ is your answer.

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