Question

yadi X + Y =√7 tatha X- Y=√8 ho to XY(X²+Y²) Ka maan kya hoga?

Answer 1

HELLO DEAR,


given that:-

X + y = √7-----------( 1 )

X - y = √8-----------( 2 )

we know that:-


(X + y)² = (x - y)² + 4xy

⇒(√7)² = (√8)² + 4xy

⇒7 - 8 = 4xy

⇒xy = -1/4---------( 3 )


now,


from--------( 1 )

(X + y)² = (√7)²

⇒x² + y² + 2xy = 7

⇒(x² + y²) = 7 - 2(-1/4)

⇒(x² + y²) = 7 + 1/2

⇒(x² + y²) = (14 + 1)/2

⇒(x² + y²) = 15/2-----------( 4 )



now,

multiply -----( 3 ) & -------( 4)

xy(x² + y²) = (-1/4)(15/2)

⇒(xy)(x² + y²) = -15/8



I HOPE ITS HELP YOU DEAR,
THANKS