# If x + y = 4 and xy = 2, find the value of x2 + y2 - Mathematics

If x + y = 4 and xy = 2, find the value of x2 + y2

#### Solution

We have:

$\left( x + y \right)^2 = x^2 + 2xy + y^2$

$\Rightarrow x^2 + y^2 = \left( x + y \right)^2 - 2xy$

$\Rightarrow x^2 + y^2 = 4^2 - 2 \times 2$    ($\because$ $x + y = 4 \text { and } xy = 2$)

$\Rightarrow x^2 + y^2 = 16 - 4$

$\Rightarrow x^2 + y^2 = 12$

Is there an error in this question or solution?

#### APPEARS IN

RD Sharma Class 8 Maths
Chapter 6 Algebraic Expressions and Identities
Exercise 6.6 | Q 10 | Page 43