Problems based on Numbers Test 3

Question : 30 of 40

Marks: +1, -0

The sum of squares of three numbers is 138, while the sum of their products taken to at a time is 131. What is their sum?

Solution:

Let the three numbers be x, y and z; then,

x^2 + y^2 + z^2 = 138

...(i)

xy + yz + zx = 131

...(ii)
Then,

(x + y + z)^2

= x^2 + y^2 + z^2 + 2(xy + yz + zx)

= 138 + 2 × 131 = 400

∴ x + y + z =√ 400 = 20

Go to Question:

Prev Question

Next Question