总述:本次共解1题。其中
☆方程1题
〖 1/1方程〗
作业:求方程 10*2.4*400*(1+a)+10*2.4*(1+a)*500*(1+2a) = 21600(1+20/9*a) 的解.
题型:方程
解:原方程:| | 10 | × | 12 5 | × | 400 | ( | 1 | + | a | ) | + | 10 | × | 12 5 | ( | 1 | + | a | ) | × | 500 | ( | 1 | + | 2 | a | ) | = | 21600 | ( | 1 | + | 20 | ÷ | 9 | × | a | ) |
| 方程左边 = | 9600 | ( | 1 | + | a | ) | + | 12000 | ( | 1 | + | a | ) | ( | 1 | + | 2 | a | ) |
方程化为:
| | 9600 | ( | 1 | + | a | ) | + | 12000 | ( | 1 | + | a | ) | ( | 1 | + | 2 | a | ) | = | 21600 | ( | 1 | + | 20 | ÷ | 9 | × | a | ) |
去掉方程左边的括号:
| 方程左边 = | 9600 | × | 1 | + | 9600 | a | + | 12000 | ( | 1 | + | a | ) | ( | 1 | + | 2 | a | ) |
| = | 9600 | + | 9600 | a | + | 12000 | ( | 1 | + | a | ) | ( | 1 | + | 2 | a | ) |
| = | 9600 | + | 9600 | a | + | 12000 | × | 1 | ( | 1 | + | 2 | a | ) | + | 12000 | a | ( | 1 | + | 2 | a | ) |
| = | 9600 | + | 9600 | a | + | 12000 | ( | 1 | + | 2 | a | ) | + | 12000 | a | ( | 1 | + | 2 | a | ) |
| = | 9600 | + | 9600 | a | + | 12000 | × | 1 | + | 12000 | × | 2 | a | + | 12000 | a | ( | 1 | + | 2 | a | ) |
| = | 9600 | + | 9600 | a | + | 12000 | + | 24000 | a | + | 12000 | a | ( | 1 | + | 2 | a | ) |
| = | 21600 | + | 33600 | a | + | 12000 | a | ( | 1 | + | 2 | a | ) |
| = | 21600 | + | 33600 | a | + | 12000 | a | × | 1 | + | 12000 | a | × | 2 | a |
| = | 21600 | + | 33600 | a | + | 12000 | a | + | 24000 | a | a |
| = | 21600 | + | 45600 | a | + | 24000 | a | a |
方程化为:
| | 21600 | + | 45600 | a | + | 24000 | a | a | = | 21600 | ( | 1 | + | 20 | ÷ | 9 | × | a | ) |
去掉方程右边的括号:
| 方程右边 = | 21600 | × | 1 | + | 21600 | × | 20 | ÷ | 9 | × | a |
方程化为:
| | 21600 | + | 45600 | a | + | 24000 | a | a | = | 21600 | + | 48000 | a |
方程化为一般式后,用因式分解法化为:
( a - 0 )( 10a - 1 )=0
由
a - 0 = 0
10a - 1 = 0
得:
a1=0
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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