Question

If N is the number of positive integral solutions of `x_1x_2x_3x_4 = 770`, then N =
A. `256`
B. `729`
C. `900`
D. `770`

Answer 1

Correct Answer - A
`(a)` `770=2xx5xx7xx11`
We can assign `2` to `x_(1)`, or `x_(2)` or `x_(3)` or `x_(4)`.
Thus `2` can be assigned in `4` ways similarly each of `5,7,11` can be assigned in `4` ways
No. of solutions `=4xx4xx4xx4=256`