ABC26GN1222 · Simplification
Subject: General Aptitude · Chapter: Simplification · Exam: · Marks: · Difficulty:
If $a=29, b=24, c=27$, the value of $a^{3}+b^{3}+c^{3}-$ $3 a b c$ is
(a)1420
(b)1520
(c)1620
(d)1920
Answer
Explanation
$a^{3}+b^{3}+c^{3}-3 a b c=(a+b+c)\left(a^{2}+b^{2}+c^{2}-a b-b c-\right.$ ca) $$\begin{aligned} & =(29+24+27)\left[(29)^{2}+(24)^{2}+(27)^{2}\right. \\ -29 \times 24-24 \times 27-27 \times 29] & \\ & =80(841+576+729-696-648- \\ & 783)=80 \times 19=1520 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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