Question

Suppose a - b = 0.
Which one of these expressions equals ab?

a. a^2
b. 0
c. 2b
d. 2a
e. a/b

Answer 1

we have that

a-b=0-----------------> a=b
b=a
therefore
a.b--------> substituting---------> a*(a)=a²   or  b*b=b²

the answer is the option A) a²