如果是整个2x的平方(2x)^2 + 4x - 5 = 0 (2x)^2 + 4x + 1 -6 = 0(2x + 1 )^2 = 6 2x + 1 = 正负√62x = -1正负√6x = (-1+√6)/2 或( -1-√6)/2；如果2的x平方2x^2+4x-5=02(x^2+2x+1)-2-5=02(x+1)^2-7=0(x+1)^2=3.5x=-1+√3.5或 -1-√3.5
2x^2+4x-5=02(x^2+2x+1)-2-5=02(x+1)^2-7=0(x+1)^2=3.5x=-1+√3.5, -1-√3.5