If the a power of 2 = m, the a power of 5 = n, then the a power of 10=---------

If the a power of 2 = m, the a power of 5 = n, then the a power of 10=---------

mn.

What does the power of a mean

It is to open the root of a n times

The sum of the three numbers a, B and C is 120. 1 / 5 of the number a is equal to 3 / 4 of the number B, which is also 3 / 5 of the number C. A? B? C?

Let a × 1 / 5 = B × 3 / 4 = C × 3 / 5 = 3x
Then a = 15x B = 4x C = 5x
15X+4X+5X=120
24X=120
X=5
therefore
A = 5 × 15 = 75
B = 5 × 4 = 20
C = 5 × 5 = 25

The ratio of the two right sides of a right triangle is 8:15, and the length of the hypotenuse is 6.8cm, so the area of the right triangle is - cm bungalow
Bowing and saluting don't need to answer questions. It's just for the task. I'm sorry

Let the two right angles be 8x and 15x respectively, that is, 64x ^ 2 + 225x ^ 2 = 6.8 * 6.8, and the solution is x = 0.4, then the two right angles are 3.2cm and 6cm long, and the triangle area is 1 / 2 (3.2 * 6) = 9.6cm square

(1) How much is 120 after 15%? 2) what is 10% less than 60?
I'm too lazy to think

(1) After an increase of 15%, it was 138
120+120*15%=138
(2) 54 is ten percent less than 60
60-6*10%=54

Let AX = B have a unique solution and a be an mxn matrix, then there must be rank (a) = n
Let AX = B have a unique solution and a be an mxn matrix, then there must be rank (a) = n
For the system of non-homogeneous linear equations AX = B, a is a matrix of order m * n, let rank (a) = R, then
When A.R = m, the system AX = B has a solution, and when b.R = n, the system AX = B has a unique solution
When C.M = n, the system AX = B has a unique solution D.R

Ax = B has a solution if R (a) = R (a | b), so D is definitely wrong, because it does not consider the augmented matrix
C is obviously not right, because M = n does not guarantee a full rank
A is obviously right, because R (a) = m, and R (a | b) cannot be larger than m, because a | B has only m rows, and its rank cannot be greater than m, so r (a) = R (a | b)
B is not guaranteed to be unique and may not exist, e.g
A=
one
two
b=
three
two
Obviously, there is no solution at this time

It takes 10 hours for a master to finish a batch of parts, and 15 hours for an apprentice to finish a batch of parts. The master processes 30 more parts per hour than the apprentice. How many parts are there?

A: there are 900 parts in this batch

7x-x+2*3=29.4 （28.8+5.5x+3.2）/2＝71

7x-x+2*3=29.4
7x-x=29.4-2*3
6x=23.4
x=23.4÷6
x=1.9
（28.8+5.5x+3.2）/2＝71
28.8+3.2+5.5x=71×2
32+5.5x=142
5.5x=142-32
5.5x=110
x=110÷5.5
x=20

The weight ratio of grain in warehouse A and warehouse B is 7:5. If 22 tons are transported from warehouse A to warehouse B, the weight ratio of grain in warehouse A and warehouse B is 2:3

If the weight of granary A is 7x, the weight of granary B is 5x
（7X-22）:（5X+22）=2:3
X = 10, that is: A, B granary weight of 70 tons, 50 tons

Solve the equation x + y + 4.2 = 12.8, 2x + 1.5y = 15

x+y+4.2=12.8
x+y=8.6 (1)
2x+1.5y=15
4x+3y=30 (2)
(2)-(1)×3
4x+3y-3x-3y=30-25.8
x=4.2
y=8.6-x=4.4