BITSAT 2013 Paper

If the sum of two positive quantities is a constant, then their product is maximum, when they are equal.
∴ a2x4. b2y2 is maximum when
a2x4 = b2y4 =

1

2

(a2x4) =

1

2

(a2x+b2y4) =

c4

2

∴ maximum value of
a2x4 . b2y4 =

c4

2

.

c4

2

=

c8

4

Maximum value of xy = (

c8

4a2b2

)1∕4 =

c2

√2ab