Question

expand the following using suitable identities (-7x +3y - 5z) ^2​

Answer 1

1) Using [(a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ca] Identity

2) Let a = -7x, b = 3y & c = -5z

3) Therefore, [(-7x) + 3y + (-5z)]² = (-7x)² + (3y)² + (-5z)² + 2(-7x)(3y) + 2(3y)(-5z) + 2(-5z)(-7x)

4) On Simplifying we get 49x² + 9y² + 25z² - 42xy - 30yz + 70zx

Answer = 49x² + 9y² + 25z² - 42xy - 30yz + 70zx

Answer 2

Step-by-step explanation:

(-7x)² + (3y)² + (-5z)² + 2(-7x)(3y) + 2(3y)(-5z) + 2(-5z)(-7x)

= 49x² + 9y² + 25z² - 42xy - 30yz + 70xz

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