I see "2^2-3/4d+1/8=0." I think you meant "2x^2-(3/4)d+(1/8)=0." If this is correct, then simplify
2x^2-(3/4)d+(1/8)=0 by mult. every term by the LCD, which is 8:
16d2 - 6d + 1 = 0
Using the quadratic formula, I obtained:
6 plus or minus sqrt(6^2 - 4(16)(1) )
d = --------------------------------------------------
2(2)
Before you do anything else, ensure that you have copied down this problem completely and correctly. Was that 2^2 or was it 2d^2? ???