Question

$if( {x}^{2} + yx - 3) = (x - 3)(x + 1)then \: y = what$

Answer 1

....................

Answer 2

⇒ ( x² + yx - 3 ) = ( x - 3 ) ( x + 1 )

⇒ ( x² + yx - 3 ) = x ( x + 1 ) - 3 ( x + 1 )

⇒ x² + yx - 3 = x² + x - 3x - 3

⇒ x² + yx = x² - 2x - 3 + 3

⇒ x² - x² + yx = -2x

⇒ yx = -2x

⇒ y = -2x / x

∴ y = -2.

Verification :

L.H.S = ( x² + yx - 3 )

          = { x² +( -2 )x - 3 }

          = ( x² - 2x - 3 ).

R.H.S = ( x - 3 ) ( x + 1 )

          = x ( x + 1 ) - 3 ( x + 1 )

          = x² + x - 3x - 3

          = x² - 2x - 3

Hence , L.H.S = R.H.S verified.

So, the value of y is ( -2 ).