总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 200×(80-50)+(80-x-50)×(200+10x)+(40-50)×[800-200-(200+10x)] = 9000 的解.
题型:方程
解:原方程:| | 200 | ( | 80 | − | 50 | ) | + | ( | 80 | − | x | − | 50 | ) | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) | = | 9000 |
去掉方程左边的括号:
| 方程左边 = | 200 | × | 80 | − | 200 | × | 50 | + | ( | 80 | − | x | − | 50 | ) | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 16000 | − | 10000 | + | ( | 80 | − | x | − | 50 | ) | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 6000 | + | ( | 80 | − | x | − | 50 | ) | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 6000 | + | 80 | ( | 200 | + | 10 | x | ) | − | x | ( | 200 | + | 10 | x | ) | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 6000 | + | 80 | × | 200 | + | 80 | × | 10 | x | − | x | ( | 200 | + | 10 | x | ) | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 6000 | + | 16000 | + | 800 | x | − | x | ( | 200 | + | 10 | x | ) | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 22000 | + | 800 | x | − | x | ( | 200 | + | 10 | x | ) | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 22000 | + | 800 | x | − | x | × | 200 | − | x | × | 10 | x | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 22000 | + | 600 | x | − | x | × | 10 | x | − | 50 | ( | 200 | + | 10 | x | ) | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 22000 | + | 600 | x | − | x | × | 10 | x | − | 50 | × | 200 | − | 50 | × | 10 | x | + | ( | 40 | − | 50 | ) |
| = | 22000 | + | 600 | x | − | x | × | 10 | x | − | 10000 | − | 500 | x | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 12000 | + | 100 | x | − | x | × | 10 | x | + | ( | 40 | − | 50 | ) | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 12000 | + | 100 | x | − | x | × | 10 | x | + | 40 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) | − | 50 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 12000 | + | 100 | x | − | x | × | 10 | x | + | 40 | × | 800 | − | 40 | × | 200 | − | 40 | ( | 200 | + | 10 | x | ) |
| = | 12000 | + | 100 | x | − | x | × | 10 | x | + | 32000 | − | 8000 | − | 40 | ( | 200 | + | 10 | x | ) | − | 50 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 36000 | + | 100 | x | − | x | × | 10 | x | − | 40 | ( | 200 | + | 10 | x | ) | − | 50 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 36000 | + | 100 | x | − | x | × | 10 | x | − | 40 | × | 200 | − | 40 | × | 10 | x | − | 50 |
| = | 36000 | + | 100 | x | − | x | × | 10 | x | − | 8000 | − | 400 | x | − | 50 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 28000 | − | 300 | x | − | x | × | 10 | x | − | 50 | ( | 800 | − | 200 | − | ( | 200 | + | 10 | x | ) | ) |
| = | 28000 | − | 300 | x | − | x | × | 10 | x | − | 50 | × | 800 | + | 50 | × | 200 | + | 50 | ( | 200 | + | 10 | x | ) |
| = | 28000 | − | 300 | x | − | x | × | 10 | x | − | 40000 | + | 10000 | + | 50 | ( | 200 | + | 10 | x | ) |
| = | - | 2000 | − | 300 | x | − | x | × | 10 | x | + | 50 | ( | 200 | + | 10 | x | ) |
| = | - | 2000 | − | 300 | x | − | x | × | 10 | x | + | 50 | × | 200 | + | 50 | × | 10 | x |
| = | - | 2000 | − | 300 | x | − | x | × | 10 | x | + | 10000 | + | 500 | x |
| = | 8000 | + | 200 | x | − | x | × | 10 | x |
方程化为一般式后,用因式分解法化为:
( 1x - 10 )( 1x - 10 )=0
由
1x - 10 = 0
1x - 10 = 0
得:
x1=10
x2=10
有 2个解。
解一元二次方程的详细方法请参阅:《一元二次方程的解法》
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