Show how to solve 8x^2+14x+5=0 by completing the square.

8 x² + 14 x + 5 = 0

2 (4 x² + 7 x) = - 5

2 (4 x² + 7 x + 49/16 - 49/16) = - 5

2 (4 x² + 7 x + 49/16) - 98/16 = - 5

2 (2 x + 7/4) ² = - 5 + 98/16

2 (2 x + 7/4) ² = - 80/16 + 98/16

2 (2 x + 7/4) ² = 18/16 = 9/8 / : 2

(2 x + 7/4) ² = 9/16 / √

2 x + 7/4 = 3/4

2 x = 3/4 - 7/4 = - 1

x = - 1

and 2 x + 7/4 = - 3/4

2 x = - 7/4 - 3/4 = - 10/4 = - 5/2

x = - 5 / 4