What is the value of x2 + 4y2 + z2 − 4xy + 4yz − 2xz?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. (2y − x + z)2.
x2 + 4y2 + z2 − 4xy + 4yz − 2xz
= x2 + (2y)2 + z2 − 2(x)(2y) + 2(z)(2y) − 2(x)(z)
= (−x)2 + (2y)2 + z2 + 2(−x)(2y) + 2(z)(2y) + 2(−x)(z)
= (2y − x + z)2