Question : If $a^2+b^2+c^2=160$ and $a+b+c=16$, find $a b+b c+c a$.
Option 1: 96
Option 2: 84
Option 3: 48
Option 4: 42
New: SSC CHSL tier 1 answer key 2024 out | SSC CHSL 2024 Notification PDF
Recommended: How to crack SSC CHSL | SSC CHSL exam guide
Don't Miss: Month-wise Current Affairs | Upcoming government exams
Correct Answer: 48
Solution :
Given, $a^2+b^2+c^2=160$ and $a+b+c=16$
We know, $(a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)$
⇒ $16^2 = 160 + 2(a b+b c+c a)$
⇒ $2(a b+b c+c a)=256-160$
⇒ $ab+bc+ca=48$
Hence, the correct answer is 48.
Related Questions
Know More about
Staff Selection Commission Combined High ...
Result | Eligibility | Application | Admit Card | Answer Key | Preparation Tips | Cutoff
Get Updates Brochure
Your Staff Selection Commission Combined Higher Secondary Level Exam brochure has been successfully mailed to your registered email id “”.
