These are exponents. To solve an exponent you need to multiply the base it self how many times its says in the power.
a²
a = base
2 = power
5³ = 5 × 5 × 5 = 125
5³ = 125
4³ = 4 × 4 × 4 = 64
4³ = 64
Check the picture below, that's the "inscribed angle theorem"
Now... let's multiply the denominator and numerator by the
conjugate of the denominator as already suggested, which is just the same, but with a different sign in the middle, 1 - i.
