Assuming that all variables are integers, the value of the expression (a = 2, B = 5, a + +, B + +, a + b) is（ A、7 B、8 C、9 D、10

Assuming that all variables are integers, the value of the expression (a = 2, B = 5, a + +, B + +, a + b) is（ A、7 B、8 C、9 D、10

Let's start with A. if the + + operator is behind the variable, it will first calculate the value of the expression and then run the + + operation. The value of the comma operator is the value of the last expression, so the result is 2 + 5 = 7. But after the expression runs, a = 3, B = 6, because the + + operation will be performed after the expression value calculation is completed

There is a mathematical formula, that is, a number has several powers

C(n,m)=n*(n-1)…… *(n-m+1)/m*(m-1)*…… 3 * 2 * 1 combination number formula
A(n,m)=n*(n-1)…… *(n-m + 1) permutation number formula

The maximum value of the function y = x-x (x ≥ 0) is______ ．

When ∵ y = x-x (x ≥ 0), ∵ y '= 12x-1, ∵ x ∈ (0,14), y' > 0, X ∈ (14, + ∞), y '< 0, ∵ x = 14, the maximum value of function y = x-x (x ≥ 0) is 14

Finding definite integral (1-1 / x ^ 2) x ^ 0.5dx
Sinxcos ^ 3xdx calculates the definite integral from 0 to 90 degrees. Another problem is f (x) = (3 + T ^ 2) ^ 0.5dt upper limit 5 lower limit x ^ 2 Finding f '(1)

(1-1/x^2)x^0.5dx
=[x^0.5-x^(-1.5)]dx
=(2 / 3) * x ^ 1.5 + 2 * x ^ (- 0.5) + C [C is constant]
You don't give the upper and lower limits, so you can only find the indefinite integral
sinxcos^3xdx
=-cos^3xd(cosx)
=-0.25(conx)^4
Substituting the upper and lower limits, we get 0.25
Let (3 + T ^ 2) ^ 0.5 be g (T), and the original function of G (T) be g (T) + C1 [C is constant]
Then f (x) = g (x ^ 2) - G (5)
There are two sides to the derivation
F '(x) = g' (x ^ 2) * (2x)
F '(x) = g (x ^ 2) * (2x) [the original function of G (T) is g (T)]
f'(x）=[(3+x^4)^0.5]*(2x)
f'(1）=4

It is urgent to take seven numbers from 1 to 9. The product of the multiplication of three numbers is equal. These three numbers are

1 2 4 8 3 6 9 this is the seven numbers taken out 4 * 3 * 6 = 8 * 9 * 1

A truck can transport ore 16 times a day in sunny days, and only 11 times a day in rainy days. It has carried ore for 17 days in a row, 222 times in total. How many days have it rained?

Suppose all the days are sunny and rainy: (16 × 17-222) / (16-11), = 50 / 5, = 10 (days); a: ten of these days are rainy

What's the sum of all the numbers from 1 to 999

9=10-1 99=100-1 999=1000-1 …… 999…… 999 (2002 9) = 1000 000 (1 followed by 2002 0) - 1, there will be a total of 2002 equations, the sum of both sides is: 9 + 99 + 999 + +999…… 999 (2002 9) = (10-1) + (100-1) + (1000-1) + +(1000…… 000 (2002 0) - 1)

Find an inequality proof. X (e ^ x)
Forget to say, there are conditions x > 0

Let f (x) = e ^ (2x) - 2E ^ (1 / 2e) 1-xe ^ x, find f '(x), Let f' (x) = 0, find x = 0, f '(x) extract e ^ x, the rest is g (x), and X > 0, G' (x) > 0, that is, x > 0, f '(x) > 0, f (x) > F (0) = 0, the inequality holds

The title is:
Fill the bottle with water. One weighs 2.4kg. Take out one third of the water in the bottle. One weighs 1.7kg. How much is the weight of the bottle
Tomorrow will be handed in, not just by a result to me, if good, I give you + points!

1 / 3 water weight 2.4-1.7 = 0.7kg
A bottle of water (without bottle) weighs 0.7 * 3 = 2.1kg
Bottle weight 2.4-2.1 = 0.3KG

The distance formula of space straight line to straight line
RT

For two different plane lines in space
Let AA 'be the line connecting any two points on two straight lines, and N1 and N2 be the direction vectors of two straight lines
The distance between two straight lines is
│(n1×n2)·AA'│