Question

using identities x-y=6: xy=4, find the value of x sqube - y sqube?

Answer 1

Hi ,

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1 ) ( x + y )² = ( x - y )² + 4xy

2 ) x² - y² = ( x + y ) ( x - y )

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Now ,

x - y = 6 ----( 1 )

xy = 4 ---- ( 2 )

( x + y )² = ( x - y )² + 4xy

= 6² + 4 × 4

= 36 + 16

= 52

x + y = √52 --- ( 3 )

x² - y² = ( x + y ) ( x - y )

= √52 × 6

= ( 2√13 ) × 6

= 12√13

I hope this helps you.

:)