If x + y + z = 7, xy + yz + zx = 8, then what is the value of x3 + y3 + z3 - 3xyz?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 175
x + y + z = 7
xy + yz + zx = 8
a3 + b3 + c3 - 3abc = (a + b + c)[(a + b + c)3 - 3(ab + bc + ac)]
Putting the values in the above formula -
x3 + y3 + z3 - 3xyz = 7(72 - 3 × 8) = 7(49 - 24) = 7(25) = 175