Let,
The number be "x"
According to the question,
x² + 5x = 176
x² + 5x - 176 = 0
x² + 16x - 11x - 176 = 0
x (x + 16) - 11 ( x + 16) = 0
(x + 16) (x - 11) = 0
Now,
Using zero product property:
Either,
x + 16 = 0
x = -16
Or,
x - 11 = 0
x = 11
So,
The number is either "-16" or "11".