If a=7, b=5, c=3, then the value of a²+b²+ c²-a b-b c-c a is · ABC26GN0201
Subject: General Aptitude · Chapter: Number System
If $a=7, b=5, c=3$, then the value of $a^{2}+b^{2}+$ $c^{2}-a b-b c-c a$ is
Answer
Explanation
$$\begin{aligned} \left(a^{2}+b^{2}+c^{2}-a b-b c-c a\right) & =(a+b+c)^{2}-3(a b+b c+c a) \\ & =(7+5+3)^{2}-3(35+15+21) \\ & =(15)^{2}-3 \times 71 \\ & =(225-213)=12 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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