RRB Assistant Loco Pilot and Technician Model Paper 6 with solutions

Question : 2 of 75

Marks: +1, -0

If p = x + y and q = x – y, then the expression

{ p + q }/ { p - q } - { p - q }/ { p + q }

has a value:

Solution:

∵ p = x + y and q = x – y
∴

{ p + q }/ { p - q } - { p - q }/ { p + q }

= { ( p ^ { 2 } + 2 p q + q ^ { 2 } ) - ( p ^ { 2 } - 2 p q + q ^ { 2 } ) }/ { p ^ { 2 } - q ^ { 2 } }

= { 4 p q } /{ p ^ { 2 } - q ^ { 2 } }

{ 4 ( x + y ) ( x - y ) }/ { ( x + y ) ^ { 2 } - ( x - y ) ^ { 2 } }

{ 4 ( x ^ { 2 } - y ^ { 2 } ) }/ { x ^ { 2 } + 2 x y + y ^ { 2 } - x ^ { 2 } + 2 x y - y ^ { 2 } }

{ x ^ { 2 } - y ^ { 2 } }/ { x y }

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