4x²+8x-1=0∴x=[-b±√(b²-4ac)]/2ax=[-8±√(8²-4×4×(-1))]/2×4 =[-8±√80]/8 =(-2±√5)/2
4x²+8x-1=04x²+8x+4-5=0(2x+2)²-5=02x+2=√5 2x+2=-√5x1=(√5-2)/2 x2=(-√5-2)/2
