Question

将方程x^+3x-4=0配方后得（x+2/3）^-4/25=0怎么判断对错

Answer 1

不对,应该是

x" + 3x - 4 = 0,

x” + 3x + (3/2)” - (9/4) - (16/4) = 0,

( x + 3/2 )” - (25/4) = 0,

配方之后,我还是分解因式解方程

( x + 3/2 )” - (5/2)" = 0,

( x + 3/2 - 5/2 )( x + 3/2 + 5/2 ) = 0,

( x - 2/2 )( x + 8/2 ) = 0,

( x - 1 )( x + 4 ) = 0,

解方程得

x1 = 1,

x2 = -4,