1.

`(sum_(x, y,z) (x +1)^(2)) - (sum_(x, y,z) (x))^(2) - 3 = ` _______A. `2[underset(x,y,z)sum x - underset(x,y,z)sum xy]`B. `3[underset(x,y,z)sum x^(2) - underset(x,y,z)sumx]`C. `2[underset(x,y,z)sum xy - underset(x,y,z)sum x^(2)]`D. `3[underset(x,y,z)sum x^(2) - underset(x,y,z)sum x]`

Answer» Correct Answer - A
`underset(x,y,z)sum (x+1)^(2) - (underset(x,y,z)sum x)^(2) -3`
`= (x +1)^(2) + (y+1)^(2) + (z +1)^(2) - (x+y+z)^(2) -3`
`= x^(2) + 2x + 1 + y^(2) + 2y + 1 + z^(2) + 2z + 1 -x^(2) -y^(2) - z^(2) -2xy - 2yz - 2zx - 3`
`= 2x + 2y + 2z - 2xy - 2yz - 2zx`
`2 underset(x,y,z)sum x -2 underset(x,y,z)sum xy = 2 (underset(x,y,z)sum x - underset(x,y,z)sum xy)`


Discussion

No Comment Found

Related InterviewSolutions