已知x²-5x=14,求(x-1)·(2x-1)-(x+1)的值.
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/02 01:04:26
![已知x²-5x=14,求(x-1)·(2x-1)-(x+1)的值.](/uploads/image/z/989211-3-1.jpg?t=%E5%B7%B2%E7%9F%A5x%26%23178%3B-5x%3D14%2C%E6%B1%82%EF%BC%88x-1%EF%BC%89%C2%B7%EF%BC%882x-1%EF%BC%89-%EF%BC%88x%2B1%EF%BC%89%E7%9A%84%E5%80%BC.)
xS]OA+4i`!.?Ť>ٗԘِ̓BKXԨuUw7B/3`X
IOw{̙3fWx&dwkоKk2@リl7i.M#CT4 Ь`D8Zie?+Uڢ?#| }6ǃu3Zz8tT8:Vnk0wH
Gҩ/JMCYtj*f
0lZjg^wqo^xilGCtҼmW!#G-l\jJ.;A#5!/R*@FPirјdbQ\"Ē&Hc4C
慧*ܰM1cwQ=pVK{wx=SwLX41
NCƻ&[C$̡~AP[V$
D7U$v~LJMԧz+PS
已知x²-5x=14,求(x-1)·(2x-1)-(x+1)的值.
已知x²-5x=14,求(x-1)·(2x-1)-(x+1)的值.
已知x²-5x=14,求(x-1)·(2x-1)-(x+1)的值.
x²-5x=14,
x²-5x-14=0,
(x-7)(x+2)=0
x=-2,7
若x=-2
(x-1)·(2x-1)-(x+1)=16
若x=7
(x-1)·(2x-1)-(x+1)=70
不懂发信~
太容易了,“(x-1)·(2x-1)-(x+1)”不够清楚。
已知x² – 5x=14
x² – 5x-14=0
(x-7)(x+2)=0
x=7 和 x=-2
分别把7和-2带进(x-1)·(2x-1)-(x+1)得70和16
16或70
x^2-5x-14=0
(x-7)(x+2)=0
x1=7,x2=-2
分别带入就行
x²-5x=14
(x+2)(x-7)=0
x=-2或x=7
1.x=-2
(x-1)·(2x-1)-(x+1)
=-3*(-5)-(-1)
=15+1=16
2.x=7
(x-1)·(2x-1)-(x+1)
=6*13-8
=78-8
=70
x²-5x=14
x²-5x-14=0
(x-7)(x+2)=0
x=7或者x=-2
(x-1)*(2x-1)-(x+1)
=2x²-3x+1-x-1
=2x²-4x
将x=7或者x=-2代入上式,得2x²-4x=16或70
(x-1)*(2x-1)-(x+1)=16或70
希望对你有帮助
由已知(x-7)(x+2)=0得x为-2huo7
分别带入,当x=-2时解得16 当x=7shi得70