Question

if(x + y) = 4 . xy = 8 then find x' + y = ?
A) 12 B) 16 CO D.) 2
ננננן​

Answer 1

Given:

X. + Y = 4

XY = 8

To find:

X² + Y²

$\huge\underline\mathbb{\red S\pink {O}\purple {L} \blue {UT} \orange {I}\green {ON :}}$

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⟹X + Y = 4

⟹Squaring both sides

⟹( X + Y) ² = (4)²

⟹By identity (a+b)² = a² + b² + 2ab

We get.

⟹X² + Y² + 2XY = 16

Now As XY = 8

⟹X² + Y² + 8×2 = 16

⟹X² + Y² = 16-16 = 0

C) 0 is the answer...

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Additional information :

⟹ Algebraic Identies are -

(a-b) ² = a² + b² -2ab

(x+a)(x+b) = x² + (a+b)x + ab

(a+b)(a-b) = a² - b²