Suppose the number of shares of investment fund A is one million, and the share of investment fund B is two million.
This problem can be described as:
50a+ 100 b & lt； = 120 ( 1)
50a * 10%+ 100 b * 4% & gt； =6, i.e. 5a+4b >；; =6 (2)
For 1, you can use Li Lian (1)(2), which is a diagram learned in high school. The solution is not unique, it is a triangular area, so I won't draw.
Pair 2, namely 50a+ 100b.
Find max{5a+4b}
It is the total investment A, that is, the total investment is 654.38+200,000, and the expected income is 654.38+200,000.
Pair 3, that is, 50a+ 100b.
Find the minimum value (8a+3b)
This solution is the only answer. As can be seen from the figure, 50a+ 100b = 120 and 5a+4b = 6 are enough at the same time.
It is obtained that: A = 0.4, B = 1, that is, Fund A invests 4000 shares and Fund B invests 1 000 shares. ..
To supplement the question, add100b >; =3 constraint, the answer remains the same. Or a fund invests 4000 copies, and b fund invests 10000 copies, with a return of 60000.