总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 -(5-x)(7-x)(10+x)-6*6*7-4*6*11+42*(7-x)+66*(5-x)+24*(10+x) = 0 的解.
题型:方程
解:原方程:| | - | ( | 5 | − | x | ) | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 6 | × | 6 | × | 7 | − | 4 | × | 6 | × | 11 | + | 42 | ( | 7 | − | x | ) | + | 66 | = | 0 |
| 方程左边 = | - | ( | 5 | − | x | ) | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 252 | − | 264 | + | 42 | ( | 7 | − | x | ) | + | 66 | ( | 5 | − | x | ) | + | 24 | ( | 10 | + | x | ) |
| = | - | ( | 5 | − | x | ) | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) | + | 66 | ( | 5 | − | x | ) | + | 24 | ( | 10 | + | x | ) |
方程化为:
| | - | ( | 5 | − | x | ) | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) | + | 66 | ( | 5 | − | x | ) | + | 24 | ( | 10 | + | x | ) | = | 0 |
去掉方程左边的括号:
| 方程左边 = | - | 5 | ( | 7 | − | x | ) | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) | + | 66 | ( | 5 | − | x | ) | + | 24 |
| = | - | 5 | × | 7 | ( | 10 | + | x | ) | + | 5 | x | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) |
| = | - | 35 | ( | 10 | + | x | ) | + | 5 | x | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) | + | 66 |
| = | - | 35 | × | 10 | − | 35 | x | + | 5 | x | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 |
| = | - | 350 | − | 35 | x | + | 5 | x | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | − | 516 | + | 42 | ( | 7 | − | x | ) |
| = | - | 866 | − | 35 | x | + | 5 | x | ( | 10 | + | x | ) | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | + | 42 | ( | 7 | − | x | ) | + | 66 |
| = | - | 866 | − | 35 | x | + | 5 | x | × | 10 | + | 5 | x | x | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) |
| = | - | 866 | − | 35 | x | + | 50 | x | + | 5 | x | x | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | + | 42 |
| = | - | 866 | + | 15 | x | + | 5 | x | x | + | x | ( | 7 | − | x | ) | ( | 10 | + | x | ) | + | 42 | ( | 7 | − | x | ) | + | 66 |
| = | - | 866 | + | 15 | x | + | 5 | x | x | + | x | × | 7 | ( | 10 | + | x | ) | − | x | x | ( | 10 | + | x | ) |
| = | - | 866 | + | 15 | x | + | 5 | x | x | + | x | × | 7 | × | 10 | + | x | × | 7 | x |
| = | - | 866 | + | 15 | x | + | 5 | x | x | + | x | × | 70 | + | x | × | 7 | x | − | x |
| = | - | 866 | + | 85 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | ( | 10 | + | x | ) |
| = | - | 866 | + | 85 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 866 | + | 85 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 866 | + | 85 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 572 | + | 43 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 572 | + | 43 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 572 | + | 43 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 242 | − | 23 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 242 | − | 23 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
| = | - | 242 | − | 23 | x | + | 5 | x | x | + | x | × | 7 | x | − | x | x | × | 10 |
方程化为一般式后,用因式分解法化为:
( x + 1 )( x - 1 )( x - 2 )=0
由
x + 1 = 0
x - 1 = 0
x - 2 = 0
得:
x1=-1
x2=1
x3=2
有 3个解。
解程的详细方法请参阅:《方程的解法》
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