Question

if x-y=2 and x square+ y square =20 then value of (x+y)hole square is
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Answer 1

Given that x-y = 2 & ........eq.1

$x {}^{2} + y {}^{2} = 20 \: \: \: \: .......eq.2$

From eq.1 square on both sides

$(x - y) {}^{2} = 2 {}^{2}$

$x {}^{2} - 2xy + y {}^{2} = 4$

$x {}^{2} + y {}^{2} = 4 + 2xy$

now the put the eq 2 in this

20 - 4 = 2xy

16 = 2xy .......eq.3

now put eq. 2 &3 in the formula

$(x + y) {}^{2} = x {}^{2} + y {}^{2} + 2xy$

$\: \: \: \: (x + y) {}^{2} = 20 + 16$

$= 36$