sin(x-1)/-1
Substitute x=1 to test this function.
In numerator, the angle is x−1 and it can be obtained in denominator as well by expressing x2−1 as two multiplying factors in which x−1 is one of them.
Therefore, the value of first multiplying factor is 1 and substitute x=1 in the second multiplying factor to obtain the required solution.
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