If the decline of the price of product a causes the supply curve of product B to move to the left, then () A. B is a substitute for a B. B is a joint product of A C. The demand of a decreases and the supply of B increases D. The supply of a decreases and the demand of B increases

If the decline of the price of product a causes the supply curve of product B to move to the left, then () A. B is a substitute for a B. B is a joint product of A C. The demand of a decreases and the supply of B increases D. The supply of a decreases and the demand of B increases

AD
The decrease of a's price will lead to the increase of a's demand, while the left shift of B's supply means the decrease of sales volume

Microeconomic topics
We know that q = 0.02m-2p, M = 7500, P = 30 yuan. When the price rises to 40 yuan, what is the price effect of price rise? What is the substitution effect? What is the income effect?

When p = 30 yuan, q = 0.02m-2p = 150-60 = 90 bottles
P = 40 yuan,
M = 7500, q = 0.02m-2p = 150-80 = 70 bottles, the price effect of price increase is 90-70 = 20 bottles
It's all substitution effect. The income doesn't change. The income effect is 0

Help do a few microeconomic problems
Suppose that a and B are competitors of the same kind and different products in a certain market, the demand curve for a is pa = 200-qa, and the demand curve for B is Pb = 300-0.5qb, and the current sales volume of the two manufacturers is QA = 50 and QB = 100, respectively; (1) what are the price elasticity of demand EDA and EDB of a and B? (2) if the price reduction of B increases the demand of B to 160, At the same time, if the demand of a is reduced to 40, what is the cross price elasticity of a's demand? (3) if B pursues the maximization of sales revenue, do you think the price reduction of manufacturer B is a correct choice?

1、edA=-3 edB=-5
2、11/6
3. Right behavior

A topic about Microeconomics
It is known that the consumer's annual income for commodity 1 and 2 is 540 yuan. The prices of the two commodities are P1 = 20 and P2 = 30 respectively. The utility function of the consumer is u = 3x1 (x2) ^ 2. What is the quantity of the two commodities each year and the total utility?

Marginal utility mu1 = 3 (x2) ^ 2 mu2 = 6X1 (x2)
MU1：p1=MU2：p2
3(x2)^2 ：20=6x1(x2)：30
12x1=9x2 x1=0.75x2
20x1+30x2=540
x1=9
x2=12
Total utility u = 3x9x12x12 = 3888