解下列方程:(1)x²-3x+2=0 (2)x²-3x-2=0 (3)x²+12x+27=0(4)(x-1)(x+2)=70 (5)(3-t)²+t²=9 (6)(y-2)²=3(7)(2x+3)²=3(4x+3) (8)(y+3)²=4(y+3)【这几个方程应该用什
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![解下列方程:(1)x²-3x+2=0 (2)x²-3x-2=0 (3)x²+12x+27=0(4)(x-1)(x+2)=70 (5)(3-t)²+t²=9 (6)(y-2)²=3(7)(2x+3)²=3(4x+3) (8)(y+3)²=4(y+3)【这几个方程应该用什](/uploads/image/z/992217-57-7.jpg?t=%E8%A7%A3%E4%B8%8B%E5%88%97%E6%96%B9%E7%A8%8B%EF%BC%9A%EF%BC%881%EF%BC%89x%26%23178%3B-3x%2B2%3D0+%EF%BC%882%EF%BC%89x%26%23178%3B-3x-2%3D0+%EF%BC%883%EF%BC%89x%26%23178%3B%2B12x%2B27%3D0%EF%BC%884%EF%BC%89%28x-1%29%28x%2B2%29%3D70+%EF%BC%885%EF%BC%89%EF%BC%883-t%EF%BC%89%26%23178%3B%2Bt%26%23178%3B%3D9+%EF%BC%886%EF%BC%89%EF%BC%88y-2%EF%BC%89%26%23178%3B%3D3%EF%BC%887%EF%BC%89%EF%BC%882x%2B3%EF%BC%89%26%23178%3B%3D3%284x%2B3%29+%EF%BC%888%EF%BC%89%28y%2B3%29%26%23178%3B%3D4%28y%2B3%29%E3%80%90%E8%BF%99%E5%87%A0%E4%B8%AA%E6%96%B9%E7%A8%8B%E5%BA%94%E8%AF%A5%E7%94%A8%E4%BB%80)
解下列方程:(1)x²-3x+2=0 (2)x²-3x-2=0 (3)x²+12x+27=0(4)(x-1)(x+2)=70 (5)(3-t)²+t²=9 (6)(y-2)²=3(7)(2x+3)²=3(4x+3) (8)(y+3)²=4(y+3)【这几个方程应该用什
解下列方程:(1)x²-3x+2=0 (2)x²-3x-2=0 (3)x²+12x+27=0
(4)(x-1)(x+2)=70 (5)(3-t)²+t²=9 (6)(y-2)²=3
(7)(2x+3)²=3(4x+3) (8)(y+3)²=4(y+3)
【这几个方程应该用什么方法做?】
解下列方程:(1)x²-3x+2=0 (2)x²-3x-2=0 (3)x²+12x+27=0(4)(x-1)(x+2)=70 (5)(3-t)²+t²=9 (6)(y-2)²=3(7)(2x+3)²=3(4x+3) (8)(y+3)²=4(y+3)【这几个方程应该用什
(1)x²-3x+2=0
x²-3x+2=(x-1)(x-2)
x=1,x=2
(2)x²-3x-2=0
x=[3+(3*3+4*2)]/2=(3+√17)/2,x=(3-√17)/2,
(3)x²+12x+27=0
x²+12x+27=(x+3)(x+9)
x=-3,x=-9
(4)(x-1)(x+2)=70
化为x²+x-72=0后配方
x²+x-72=(x-8)(x+9)
(5)(3-t)²+t²=9
方法一:直接看出t=0,t=3
方法一:化为2t²-6t=0后配方得解
t=0,t=3
(6)(y-2)²=3
两端开平方得y-2=±√3得解
y=2±√3
(7)(2x+3)²=3(4x+3)
化简为(2x+3)²-3(4x+6) +9=0分解为
(2x+3-3)²=0
x=0
(8)(y+3)²=4(y+3)
右侧移至左侧后提取公因式得
(y+3)(y+3-4)=0
y=-3,y=1