总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 (80-50)*200+(80-X-50)*(200+10X)+(40-50)*(400-10X) = 9000 的解.
题型:方程
解:原方程:| | ( | 80 | − | 50 | ) | × | 200 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) | = | 9000 |
去掉方程左边的括号:
| 方程左边 = | 80 | × | 200 | − | 50 | × | 200 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 16000 | − | 10000 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | ( | 80 | − | X | − | 50 | ) | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 80 | ( | 200 | + | 10 | X | ) | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 80 | × | 200 | + | 80 | × | 10 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 6000 | + | 16000 | + | 800 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 800 | X | − | X | ( | 200 | + | 10 | X | ) | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 800 | X | − | X | × | 200 | − | X | × | 10 | X | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 22000 | + | 600 | X | − | X | × | 10 | X | − | 50 | ( | 200 | + | 10 | X | ) | + | ( | 40 | − | 50 | ) | ( | 400 | − | 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 | ) | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | ( | 40 | − | 50 | ) | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 40 | ( | 400 | − | 10 | X | ) | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 40 | × | 400 | − | 40 | × | 10 | X | − | 50 |
| = | 12000 | + | 100 | X | − | X | × | 10 | X | + | 16000 | − | 400 | X | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 50 | ( | 400 | − | 10 | X | ) |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 50 | × | 400 | + | 50 | × | 10 | X |
| = | 28000 | − | 300 | X | − | X | × | 10 | X | − | 20000 | + | 500 | X |
| = | 8000 | + | 200 | X | − | X | × | 10 | X |
方程化为:
| | 8000 | + | 200 | X | − | X | × | 10 | X | = | 9000 |
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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