Question : If a + b + c = 19, ab + bc + ca = 120, then what is the value of a3 + b3 + c3 – 3abc?
Option 1: 18
Option 2: 23
Option 3: 31
Option 4: 19
Answer (1)
18th Jan, 2024
Correct Answer: 19
Solution :
Given,
a + b + c = 19 and ab + bc + ca = 120
We know,
a
3
+ b
3
+ c
3
– 3abc = (a + b + c) [(a + b + c)
2
– 3(ab + bc + ca)]
= 19[19
2
– 3 × 120]
= 19[361 – 360]
= 19 × 1
= 19
Hence, the correct answer is 19.
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