Given 21x² – 28x + 10 = 0

Recall that the roots of quadratic equation ax² + bx + c = 0, where a ≠ 0, are given by

Here, a = 21, b = –28 and c = 10

We have i² = –1

By substituting –1 = i² in the above equation, we get

Thus, the roots of the given equation are.