总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 (11-x)*(5-x)*(2-x)-160-160-4(5-x)-64(2-x)-100(11-x) = 0 的解.
题型:方程
解:原方程:| | ( | 11 | − | x | ) | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 160 | − | 160 | − | 4 | ( | 5 | − | x | ) | − | 64 | ( | 2 | − | x | ) | − | 100 | ( | 11 | − | x | ) | = | 0 |
| 方程左边 = | ( | 11 | − | x | ) | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) | − | 64 | ( | 2 | − | x | ) | − | 100 | ( | 11 | − | x | ) |
方程化为:
| | ( | 11 | − | x | ) | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) | − | 64 | ( | 2 | − | x | ) | − | 100 | ( | 11 | − | x | ) | = | 0 |
去掉方程左边的括号:
| 方程左边 = | 11 | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) | − | 64 | ( | 2 | − | x | ) | − | 100 |
| = | 11 | × | 5 | ( | 2 | − | x | ) | − | 11 | x | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) |
| = | 55 | ( | 2 | − | x | ) | − | 11 | x | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) | − | 64 |
| = | 55 | × | 2 | − | 55 | x | − | 11 | x | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 |
| = | 110 | − | 55 | x | − | 11 | x | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 320 | − | 4 | ( | 5 | − | x | ) |
| = | - | 210 | − | 55 | x | − | 11 | x | ( | 2 | − | x | ) | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 4 | ( | 5 | − | x | ) | − | 64 |
| = | - | 210 | − | 55 | x | − | 11 | x | × | 2 | + | 11 | x | x | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) |
| = | - | 210 | − | 55 | x | − | 22 | x | + | 11 | x | x | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 4 |
| = | - | 210 | − | 77 | x | + | 11 | x | x | − | x | ( | 5 | − | x | ) | ( | 2 | − | x | ) | − | 4 | ( | 5 | − | x | ) | − | 64 |
| = | - | 210 | − | 77 | x | + | 11 | x | x | − | x | × | 5 | ( | 2 | − | x | ) | + | x | x | ( | 2 | − | x | ) |
| = | - | 210 | − | 77 | x | + | 11 | x | x | − | x | × | 5 | × | 2 | + | x | × | 5 | x |
| = | - | 210 | − | 77 | x | + | 11 | x | x | − | x | × | 10 | + | x | × | 5 | x | + | x |
| = | - | 210 | − | 87 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | ( | 2 | − | x | ) |
| = | - | 210 | − | 87 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 210 | − | 87 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 210 | − | 87 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 230 | − | 83 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 230 | − | 83 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 230 | − | 83 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 358 | − | 19 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 358 | − | 19 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 358 | − | 19 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
| = | - | 1458 | + | 81 | x | + | 11 | x | x | + | x | × | 5 | x | + | x | x | × | 2 |
方程化为一般式后,用因式分解法化为:
( x + 9 )( x - 9 )( x - 18 )=0
由
x + 9 = 0
x - 9 = 0
x - 18 = 0
得:
x1=-9
x2=9
x3=18
有 3个解。
解程的详细方法请参阅:《方程的解法》
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