总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 100×800×(1-a/100)×(1+20/100)+200×600×(1-a/100)×(1+3a/100) = 108000 的解.
题型:方程
解:原方程:| | 100 | × | 800 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 20 | ÷ | 100 | ) | + | 200 | × | 600 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) | = | 108000 |
| 方程左边 = | 80000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
方程化为:
| | 80000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) | = | 108000 |
去掉方程左边的括号:
| 方程左边 = | 80000 | × | 1 | ( | 1 | + | 20 | ÷ | 100 | ) | − | 80000 | a | ÷ | 100 | × | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 80000 | ( | 1 | + | 20 | ÷ | 100 | ) | − | 800 | a | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 80000 | × | 1 | + | 80000 | × | 20 | ÷ | 100 | − | 800 | a | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 80000 | + | 16000 | − | 800 | a | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 800 | a | ( | 1 | + | 20 | ÷ | 100 | ) | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 800 | a | × | 1 | − | 800 | a | × | 20 | ÷ | 100 | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 800 | a | − | 160 | a | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 960 | a | + | 120000 | ( | 1 | − | a | ÷ | 100 | ) | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 960 | a | + | 120000 | × | 1 | ( | 1 | + | 3 | a | ÷ | 100 | ) | − | 120000 | a | ÷ | 100 | × | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 960 | a | + | 120000 | ( | 1 | + | 3 | a | ÷ | 100 | ) | − | 1200 | a | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 960 | a | + | 120000 | × | 1 | + | 120000 | × | 3 | a | ÷ | 100 | − | 1200 | a | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 96000 | − | 960 | a | + | 120000 | + | 3600 | a | − | 1200 | a | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 216000 | + | 2640 | a | − | 1200 | a | ( | 1 | + | 3 | a | ÷ | 100 | ) |
| = | 216000 | + | 2640 | a | − | 1200 | a | × | 1 | − | 1200 | a | × | 3 | a | ÷ | 100 |
| = | 216000 | + | 2640 | a | − | 1200 | a | − | 36 | a | a |
| = | 216000 | + | 1440 | a | − | 36 | a | a |
方程化为:
| | 216000 | + | 1440 | a | − | 36 | a | a | = | 108000 |
方程的解为:
a1≈-38.309519 ,保留6位小数
a2≈78.309519 ,保留6位小数
有 2个解。
解程的详细方法请参阅:《方程的解法》
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