SSC CHSL 12 Oct 2020 Shift 2 Paper

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Question : 72 of 100

Marks: +1, -0

If

a+b=11

and

a b=15

, then

a^{2}+b^{2}

is equal to

91
92
93
90

Solution:

a+b=11

(squaring on both sides)
⇒

a^{2}+b^{2}+2 a b=121

⇒

a^{2}+b^{2}+2 \×15=121

⇒

a^{2}+b^{2}+30=121(\∵a b=15)

⇒

a^{2}+b^{2}=91

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