4x2 +7x -2=0

(4x-1)(x+2) = 0

4x^2 + 7x - 2 = 0

well you can use the quadratic equation
x = [ -7 +/-sqrt (49 + 32) ] / 8
= [ -7 +/- 9 ] / 8
= -2 or 1/4
or factor
( x + 2)(4 x-1) = 0