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Seratul Seratul
  • 25-02-2017
  • Mathematics
Answered

If \(x^{2} -y^{2} =21\), then \(2(x+y)(x-y)=\)

A21/2
B18
C21
D42

Please explain.

Verified Answer :

ChandrikaP ChandrikaP
  • 25-02-2017

Answer is D 42
\(x^{2} - y^{2} =(x+y)(x-y)\)
It is given
=21
Multiply both side by 2
U will bet 21×2=42

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