If a-b=3 and a²+b²=29, find the value of a b. · ABC26GN1203

Subject: General Aptitude · Chapter: Simplification · Exam: R.R.B. 2003

If $a-b=3$ and $a^{2}+b^{2}=29$, find the value of $a b$.

(a)10

(b)12

(c)15

(d)18

Answer

Answer (as printed): A

Explanation

$$2 a b=\left(a^{2}+b^{2}\right)-(a-b)^{2}=29-9=20 \Rightarrow a b=10 .$$

Explanation as extracted from the printed page; notation may be imperfect.

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