Tìm cực trị của hàm số: z = x2 + y2 + xy + x – y

The contents of 3838 cans of coke have a mean of x¯¯¯=12.15x¯=12.15. assume the contents of cans of coke have a normal distribution with standard deviation of σ=0.12.σ=0.12. find the value of the test statistic zz for the claim that the population mean is μ=12.μ=12.

The perimeter of a stage is 116 feet. it is 17 feet wide. how long is it?

Afarmer sells 9.5 kilograms of apples and pears at the farmer's market. 4/5 of the weight is the apples and the rest is the pears. how many kilograms of pears did she sell at the farmers market