Subtract 1 to put the equation in general form (also called Standard Form in the US).
2x² + 5x - 1 = 0
The value of b²-4ac is found by substituting the values of a, b, c in that expression. In this equation,
a=2
b=5
c=-1
b²-4ac = 5²-4(2)(-1) = 25+8
b²-4ac = 33
