用(公式法)解方程:x²+x-2=0 x²-4x+2=0 4x²-3x-5=x-2 3x(x-3)=2(x-1)(x+1),①x²+x-2=0 ②x²-4x+2=0③4x²-3x-5=x-2④3x(x-3)=2(x-1)(x+1)
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![用(公式法)解方程:x²+x-2=0 x²-4x+2=0 4x²-3x-5=x-2 3x(x-3)=2(x-1)(x+1),①x²+x-2=0 ②x²-4x+2=0③4x²-3x-5=x-2④3x(x-3)=2(x-1)(x+1)](/uploads/image/z/226824-24-4.jpg?t=%E7%94%A8%EF%BC%88%E5%85%AC%E5%BC%8F%E6%B3%95%EF%BC%89%E8%A7%A3%E6%96%B9%E7%A8%8B%EF%BC%9Ax%26%23178%3B%2Bx-2%3D0+x%26%23178%3B-4x%2B2%3D0+4x%26%23178%3B-3x-5%3Dx-2+3x%28x-3%29%3D2%28x-1%EF%BC%89%EF%BC%88x%2B1%EF%BC%89%2C%E2%91%A0x%26%23178%3B%2Bx-2%3D0+%E2%91%A1x%26%23178%3B-4x%2B2%3D0%E2%91%A24x%26%23178%3B-3x-5%3Dx-2%E2%91%A33x%28x-3%29%3D2%28x-1%EF%BC%89%EF%BC%88x%2B1%EF%BC%89)
用(公式法)解方程:x²+x-2=0 x²-4x+2=0 4x²-3x-5=x-2 3x(x-3)=2(x-1)(x+1),①x²+x-2=0 ②x²-4x+2=0③4x²-3x-5=x-2④3x(x-3)=2(x-1)(x+1)
用(公式法)解方程:x²+x-2=0 x²-4x+2=0 4x²-3x-5=x-2 3x(x-3)=2(x-1)(x+1),
①x²+x-2=0
②
x²-4x+2=0③
4x²-3x-5=x-2
④
3x(x-3)=2(x-1)(x+1)
用(公式法)解方程:x²+x-2=0 x²-4x+2=0 4x²-3x-5=x-2 3x(x-3)=2(x-1)(x+1),①x²+x-2=0 ②x²-4x+2=0③4x²-3x-5=x-2④3x(x-3)=2(x-1)(x+1)
x²+x-2=0
Δ=1+8=9
所以x=(-1±根号9)/2=(-1±3)/2
即x1=-2.x2=1
x²-4x+2=0
Δ=16-8=6
所以x=(4±根号8)/2=2±2根号2
4x²-3x-5=x-2
方程转化为4x^2-4x-3=0
Δ=16+48=64
所以x=(4±根号64)/8
即x1=1.5,x2=-0.5
3x(x-3)=2(x-1)(x+1)
方程转化为x^2-9x+2=0
Δ=81-8=73
所以x=(9±根号73)/2