40 minutes = () hours 5 cm = () meters 750 kg = () tons 120 square decimeters = () square meters Answer with marks

40 minutes = () hours 5 cm = () meters 750 kg = () tons 120 square decimeters = () square meters Answer with marks

2/3
1/20
3/4
6/5

[1 / 2 (x + 1)] 2 ^ - 2 [1 / 2 (x + 1)] + 2 why is it reduced to 1 / 4 (x2 ^ - 2x + 5), note: 1 / 2 is half, 2 ^ table is square
[1 / 2 (x + 1)] 2 ^ - 2 [1 / 2 (x + 1)] + 2 why is it 1 / 4 (x2 ^ - 2x + 5) after simplification,
Note: 1 / 2 is half
2 ^ table is square

[1/2(x+1)]2^ → 1/4*（X+1）2^ → 1/4*（X2^+2X+1）
-2[1/2(x+1)] → -4*1/4*（X+1） → 1/4*（-4X-4）
+2 → +8*1/4 → 1/4*（+8）
Not yet. You can go home!

Known samples x1, X2 If the variance of XN is 2, then the sample is 3x1 + 2, 3x2 + 2 The variance of 3XN + 2 is______ ．

∵ samples x1, X2 If the variance of XN is 2, and each data in a set of data is expanded several times, the variance of the new data will be expanded by its square times The variance of 3XN is 32 × 2 = 18, ∵ after adding the same number to each data in a group, the variance of the new data is equal to that of the original data, ∵ sample 3x1 + 2, 3x2 + 2 The variance of 3XN + 2 is 18

-5 + 7-12 + 136-88-4 1 / 3 - 5 1 / 2 + 7 1 / 3 - 10.8

Is this a math problem? If you do, it's 24.7

Five and three fifths × two and one seventh - 1.2 × one and one third + twelve and one half equals ()

Five and three fifths × two and one seventh - 1.2 × one and one third + twelve and one half
=28/5×15/7-1.2×4/3+12.5
=12-1.6+12.5
=22.9

One third to () = one half to three seventh

One third to (two out of seven) = one half to three out of seven

Use the five numbers half, one third, one fourth, one fifth and one sixth to form the formula of addition and subtraction and write the number

For example: 1 / 2-1 / 3 + 1 / 4-1 / 5 + 1 / 6 = (30-20 + 15-12 + 10) / 60 = 23 / 60

How many addition and subtraction formulas can be formed by taking any two numbers from 160720250?

6
160+（-）720
160+（-）250
720+（-）250

English addition and subtraction: do the following addition and subtraction, and finally form a word
Example: ship + to hi = (stop)
1.stay-y+act-c+r-a=( )
2.nine-ne+toy-o=( )
3.strong-ong+meet-m=( )
4.hill+age-h+v=( )
5.door+act-a=( )
6.plane+o-an+ice-e=( )

1 start
2 nity tiny
3 street
4 village
5 doctor
6 police

720 + (720 + 144) + (720 + 144 * 2) + (720 + 144 * 3) +. + (720 + 144 * 49) =?
Don't forget the formula for a long time!

720+（720+144）+（720+144*2）+（720+144*3）+.+（720+144*49）=
720*50+144*（1+49）*49/2