If a + b + c = 7 and ab + bc + ca = -6, then the value of a3 + b3 + c3 − 3abc is:
Answer & explanation
Correct answer: option 1
If x + y = n
then, $x^3 + y^3$ = n3 - 3 × n × xy
If a + b + c = 7
ab + bc + ca = -6
Then the value of a3 + b3 + c3 − 3abc = ?
If the number of equations are less than the number of variables then we can put the extra variables according to our choice =
So here two equations given and three variables are present so put c = 0
If a + b = 7
ab = -6
Then the value of a3 + b3 = 73 - 3 × 7 × -6
a3 + b3 = 469