解:x^2-2x-4=10
移项: x^2-4x-4-10=0.
合并常数项:x^2-4x-14=0.
解法一. 用公式法:x1,2={-(-4)±√[(-4)^2-4*1*(-14)]}/2*1.
x1,2=[4±√(16+56)]/2.
=(4±√72)/2.
=(4±6√2)/2.
=2±3√2.
x1=2+3√2;
x2=2-3√2.
解法二. 用配方法:
x2-4x+4-4-14=0
(x-2)^2-4-14=0.
(x-2)^2=18.
x-2=±√18.
x=2±3√2.
x1=2+3√2;
x2=2-3√2.
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