解
(2x-1)²-7=3(x+1)
4x²-4x+1-7=3x+3
4x²-4x-6=3x+3
4x²-4x-3x-6-3=0
4x²-7x-9=0
公式法求根
△=b²-4ac=49+4×4×9=193
∴
x=(7+√193)/8
或x=(7-√193)/8(7+??193)/8?????????7+??193??????????8?????????????????￡?лл??????ax²+bx+c=0x=(-b+???)/2a??=b²-4ac4x²-7x-9=0b=-7??a=4??c=-9??=b²-4ac=49+4??4??9=193??x=(7+??193)/8(-b+???????)/2a??????2a???????-b+????????????????????????????=b?????-4ac??????????x=[-b+??(b²-4ac)]/2ax=[-b-??(b²-4ac)]/2a