Question

What would be the value of Pearson’s r (simply the square root of r2)? R² = 0.785

Answer 1

R^2 = 0.785

Take the square root of both sides

√R^2 = √0.785
R= 0.886

Answer 2

Every equation that has anything squared in it is
going to have two solutions.

The solutions of      R² = 0.785

are                          R = 0.886... (rounded)
and                         R = -0.886... (rounded) .

When you multiply EITHER of those numbers by itself, you get
0.785 , so both of them make the equation a true statement.