Question

Expand using suitable identities
(x - 2y + 5z)²​

Answer 1

Answer:

(x - 2y + 5z)²​ = x² + 4y² + 25z² -4xy -20yz + 10xz

Step-by-step explanation:

(a - b + c)² = [a + (- b) + c]²

= a² + (-b²) + c² + 2 (a) (-b) + 2 (-b) (-c) + 2 (c) (a)

= a² + b² + c² – 2ab – 2bc + 2ca

Therefore, (a - b + c)² = a² + b² + c² – 2ab – 2bc + 2ca

Given: (x - 2y + 5z)²​

a = x, b = 2y and c = 5z

So,  (x - 2y + 5z)²​ =  (x)² +(2y)² + (5z)² - 2 (x)(2y) - 2 (2y)(5z) + 2 (5z) (x)

= x² + 4y² + 25z² -4xy -20yz + 10xz