Mathematics in the first year of junior high school Volume 2 exercise book page 1 question 10

Mathematics in the first year of junior high school Volume 2 exercise book page 1 question 10

2 + M = 0, M = - 2, 3n-1 = 0, n = 1 / 3, 2m + 3N = 2 × - 2 + 3 × 1 / 3 = - 4 + 1 = - 3

How to do question 4 on page 10 of the first year's mathematics exercise book

10. From the known values of X and y, we can substitute 2aX by = 2 to get 2a-b = 2 and - 2A 2B = 2, we can get a = 3 and B = 4, that is, the value of a B is 7.11. First, we transform x y = 12 into x = 12-y, and then substitute it into

1. A person sells both a and B shares. The A shares sell for 1200 yuan, making a profit of 20%. The B shares also sell for 1200 yuan, but losing 20%. Is the person making a profit or losing money in this transaction? How much is the profit or loss?
2. Party A and Party B go along the highway at an average speed. Party A travels 3 kilometers per hour and Party B travels 5 kilometers per hour. Party A passes city a at 12 noon and Party B passes city a at 2 pm. Ask Party B what time in the afternoon they can catch up with Party a. how far are they from city a at this time?

Oh, don't worry about the upstairs
The original price of a's stock is x yuan
(100%+20%)x=1200
120%x=1200
x=1200/120%
x=1000
The original price of B stock is x yuan
(100%-20%)x=1200
80%x=1200
x=1200/80%
x=1500
A; Ying; 1200-1000 = 200 (yuan)
B; loss; 1500-1200 = 300 (yuan)
300-200 = 100 yuan
A: a loss of 100 yuan
2 pm = 14:14-12 = 2 (hours) 2 * 3 = 6 (kilometers)
Let B catch up with a in X hours
5x=3x+6
2x=6
x=3
14 + 3 = 17 hours 17 hours = 5 pm
3 * 5 = 15 (km)
A: at 5 pm, B overtakes a, 15 km away from a city

Two mathematics problems in grade one of junior high school
① To prepare 1000 kg of 10% sulfuric acid solution, there are 85 kg of 60% sulfuric acid. How many kg of 98% sulfuric acid and water are needed?
② Cut two pieces of equal weight from two pieces of alloy weighing 20 kg and 30 kg respectively with different copper content and percentage. Add all the remaining pieces and the rest of the other piece. After smelting, the percentage of copper content of the two pieces is exactly equal. What is the weight of the cut piece

1. Solution, let x kg water be added
1000*10%=85*60%+98%（100*10-85*60%-X）+X
100=51+48.02+2%X
100-99.02=2%X
X=49
I can't do question 2. I don't understand it. I'm a junior one

7 / 18 △ 3 × 1 / 2 △ 2 / 3 = 7 / 18 compare the first number with the result
What do you find by comparing the first number with the last one? Why?

The title is wrong, so the final result is 7 / 72
Which symbols should be wrong
But let me tell you the idea
The number after 7 / 18 can be enclosed in brackets
Then, in the brackets, what turned out to be x becomes △ what turned out to be △ becomes ×
Finally, the number in brackets is 1
So the answer must be the same as the first number

4+6×（3x-2)=16x 13x-4(2x+5)=17(x-2)-4(2x-1)

4+6×(3x-2)=16x
4+18x-12=16x
18x-16x=12-4
2x=8
x=4
13x-4(2x+5)=17(x-2)-4(2x-1)
13x-8x-20=17x-34-8x+4
5x-20=9x-30
9x-5x=30-20
4x=10
x=2.5

Simple calculation of 4.67 * 1.8 + 46.7 * 0.18
By the way, teach me another question, (190-56.4 divided by 3) × 0.45, 7.23-1.25 × 4-0.7,

4.67*1.8+46.7*0.18
4.67*1.8+4.67*1.8
4.67*（1.8+1.8）
4.67*3.6
sixteen point eight one two

It is known that the image of a linear function passes through a (1.6) and is parallel to the straight line y = - 2x
(1) (2) if point B (a, 2) is on the function image, find the value of a; (3) let o be the coordinate origin, find the function expression of OB line

(1) Let the expression of this function be: y = - 2x + B, because its image passes through a (1.6), 6 = - 2 + B, B = 8, so the expression of this function is: y = - 2x + 8; (2) from the point B (a, 2) on this function image: 2 = - 2A + 8, a = 3 (3) let the function expression of OB's line be y = KX, then: 2 = 3k, k = 2 / 3, so o

(1) think of a number. Add 5 to the number, multiply by 4, subtract 20, multiply by 2, and divide by 8. You must get the number you originally thought
(2) suppose that the number you want is a, write the algebraic formula according to the calculation steps in (1) and simplify it. What do you find?
(3) please make up a math game for yourself

Let this number be a
[(a+5)*4-20]*2/8
=(4a+20-20)/4
=a
So the final result is also a
No matter what the value of a is, the result is a after operation
(3) Add 5 to this number, multiply by 3, then subtract 6, multiply by 2, and finally divide by 6, subtract 3. You must get the number you originally thought

If f (x) = loga (2-logax)

What do you want?