Kyle M. answered • 12/02/16

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Only the first one here is a fraction, so perhaps you copied the second one incorrectly. Nonetheless, we can certainly solve the fraction.

As fractions are considered "undefined" if the denominator equals zero, the only way for a fraction to equal zero is for the numerator to equal zero - no matter the value of the denominator. In the case of x(x+1)/x+4, either x=0 or x+1=0. So:

0(0+1)/0+4 = 0/4

or

x+1=0

x=0-1

x=-1

-1(0)/-1+4 = 0/3

So, x=-1 & x=0 will make the fraction equal zero.