The sum of the squares of three numbers is 138, while the sum of their products taken two at a time is 131. Their sum is:

A. 20

B. 30

C. 40

D. None of these


Option A. 20 is the right answer

Aptitude Questions stylish banner by CSSMCQs
Aptitude Questions by CSS MCQs
Let suppose The sum of the squares of three numbers is 138 i.e
  a2 + b2 + c2 = 138
And, the sum of their products taken two at a time is 131 i.e
(ab + bc + ca) = 131
Now, as we know that
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca)
By putting the values, we get
(a + b + c)2 = 138 + 2 x 131
(a + b + c)2 =   400
By taking under root on both sides, we get
(a + b + c)2 =   400

(a + b + c)  = 20

Hence, if the sum of the squares of three numbers is 138, while the sum of their products taken two at a time is 131. Thenm their sum is 20 as proved above.

which is our right answer:)



Click Here to Submit MCQs

CSSMCQs Android APK app download image showing

Click Here for Online MCQs Quiz Now

Click Here to Submit MCQs

Register if you don't have an Account.

🏠 Home

If the aforementioned Answer is Wrong. Leave a Reply with an authentic source.