Find all values of m that will make 1/((m^2-6m-7)/(m^2-49)) undefined.

Question

a)-1 only

b)-1 & 7 only

c)0 & 7 only

d)-1, -7 & 7 only

Answer 1

Take the denominator fraction: (m²-6m-7)/(m²-49)=(m-7)(m+1)/((m-7)(m+7))=(m+1)/(m+7) provided m≠7. This is undefined for m=-7.

The reciprocal of this fraction is (m+7)/(m+1). This is undefined for m=-1.

Therefore the expression satisfies option d.