RRB Junior Engineer Stage 1 Model Papers 2

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Question : 26 of 99

Marks: +1, -0

If

a + b + c = 2s

, then

{(s-a)^2+(s-b)^2+(s-c)^2+s^2}/{a^2+b^2+c^2}

is equal to

$a^2+ b^2+ c^2$
0
1
2

Solution:

Expression

={(s-a)^2+(s-b)^2+(s-c)^2+s^2}/{a^2+b^2+c^2}

={s^2-2sa+a^2+s^2+b^2-2sb+s^2-2sc+c^2+s^2}/{a^2+b^2+c^2}

={4s^2+a^2+b^2+c^2-2s(a+b+c)}/{a^2+b^2+c^2}

={4s^2+a^2+b^2+c^2-4s^2}/{a^2+b^2+c^2}=1

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