SSC CGL 2019 PYQ — Question 55

SSC CGL - 4th June 2019 - Shift 2 • Quantitative Aptitude • Q55

If x + y + z = 19, xy + yz + zx = 114, then the value of √(x3 + y3 + z3 – 3xyz) is:

Show answer & explanation

Correct answer: D

Explanation

Correct Answer is option 4 i.e. 19

Concept

Understanding

Application

Formula:

a3 + b3 + c3 – 3abc = (a + b + c) [(a + b + c)2 – 3(ab + bc + ca)]

Given

x + y + z = 19, 

xy + yz + zx = 114

Applying the formula:

x3 + y3 + z3 – 3xyz = 19 × [192 – 3 × 114]

= 19 × [361 – 342]

= 19 × 19

Hence,

√(x3 + y3 + z3 – 3xyz) = 19