CTET 2 Math and Science Dec 2019 Paper

Question : 46 of 120

Marks: +1, -0

The expression

(x - y) (x^2 + xy + y^2)

+ (x + y) (x^2 - xy + y^2)

- (x + y)(x^2 - y^2)

is equal to

Solution:

The expression =

(x- y)(x^ 2 + xy + y^ 2 )

+ (x + y) (x^ 2 -xy + y^ 2 )

- (x + y)(x^ 2 -y^ 2 )

= x^ 3 - y^ 3 + x^ 3 + y^ 3

- (x^ 3 - xy^2 + x ^2y- y^ 3 )

= 2x^ 3 - x^ 3 + xy^2 - x^ 2y + y^ 3

= x^ 3 + y^ 3 + xy(y - x)

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