The average number of a, B and C is 60. The ratio of a, B and C is 3:2:1. What are the numbers of a, B and C

The average number of a, B and C is 60. The ratio of a, B and C is 3:2:1. What are the numbers of a, B and C

Method 1: 60 * 3 = 180 is the total number 3 + 2 + 1 = 6, a total of 6 copies 180 / 6 = 30, this is the number of a 30 * 3 = 90, B 30 * 2 = 60, C is a 30
Method 2: 60 * 3 = 180 is the total number of 3 + 2 + 1 = 6, a total of 6 parts are distributed according to proportion a: 180 × 3 / 6 = 90 B: 180 * 2 / 6 = 60 C: 180 * 1 / 6 = 30

Define the operation a * B as: a * b = a (AB), for example, 1 * 2 = 1, then the value range of 1 * 2 ^ X

According to the definition of operation,
If 2 ^ x > = 1, 1 * 2 ^ x = 1
If 2 ^ X0
So the value range of 1 * 2 ^ x is (0,1]

The sum of a and B is 16.5, the decimal point of a moves one place to the right, which is exactly the number of B, and the number of a is ()
A. 15B. 1.5C. 8.75D. 11

A: the number of a is 1.5

It is known that the quadratic equation (1 + a) x & sup2; + 2x + 1-A = 0 has two integer roots. Find the maximum and minimum of the real root a

Obviously a is not equal to - 1
The factorization result is: [(1 + a) x + 1-A] * (x + 1), so the two heels are - 1 and (1-A) / (1 + a) = integers
(1-A) / (1 + a) = integer = [2 / (1 + a)] - 1
That is, integer = 2 / (1 + a)
There must be an absolute value of 1 + a = 2, so - 3

The average number of a, B and C is 130. The known number a is 150, the number B is 99, and what is the number C?

The average number of a, B and C is 130. It is known that a is 150, B is 99 and C is (141)
130×3-150-99
=390-150-99
=240-99
=141
If you don't understand, please ask

Let a be a matrix of order n and B be a non-zero matrix of order n. if every column vector of B is the solution of the system of homogeneous linear equations AX = 0, then | a | =? Seek the solution~
Such as the title~
I'm so stupid
Corollary: if there is a nonzero solution to the n-gore equation, the homogeneous linear equations AX = 0 with n unknowns, then | a | = 0

|A|=0
prove:
Let R be the rank of matrix A of order n. when r = n, the homogeneous linear equations AX = 0 have only zero solutions
But every column vector of n-order nonzero matrix B is the solution of homogeneous linear equation AX = 0, so AX = 0 has nonzero solution, then r < n, thus | a | = 0

How many hours does it take for worker a to process 36 parts in 4 hours, worker B to process 56 identical parts in 7 hours, and two workers to process 170 parts at the same time? When completing the task, how many parts will each process?

170 △ (36 △ 4 + 56 △ 7) = 10 hours
A 36 △ 4 × 10 = 90
B 56 △ 7 × 10 = 80

The solution of the system of binary linear equations x + y = 5kx − y = 9K is the solution of binary linear equations 2x + 3Y = 6, then the value of K is ()
A. k＝−34B. k＝34C. k＝43D. k＝−43

If x + y = 5kx − y = 9K, then x = 7ky = − 2K, and then substitute into the equation 2x + 3Y = 6, then 14k-6k = 6, then k = 34, so choose B

Warehouse A and warehouse B store a batch of grain. The stock of warehouse a accounts for 5 / 8 of this batch of grain, which is 45 tons more than that of warehouse B. how many tons are there in total?
wait anxiously

Let the total be XT. Then a has 5 / 8 * x tons and B has 5 / 8 * x-45 tons. So 5 / 8 * x + 5 / 8 * x-45 = x, and the solution is x = 180

Calculation question 7x (2-x) = 3 (X-2)
7x(2-x)=3(x-2)
(Note: the "X" in "7x" is the letter "X", not a multiplication sign)

7x(2-x)=3(x-2)
14x-7x²=3x-6
7x²+(3-14)x-6=0
7x²-11x-6=0
(7x+3)(x-2)=0
x1=-3/7 x2=2