Solve the equation 3x + 15% x = 69,

Solve the equation 3x + 15% x = 69,

3X+15%X=69
（3+15%）x=69
(63/20)x=69
x=69×20/63=460/21

Mp3 analysis of words in English compulsory one person edition of experimental textbook of senior high school curriculum standard

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A list of English compulsory 1 and compulsory 2 words in the experimental textbook of the curriculum standard for senior high school
Word list, word list, just like a book,

Three numbers a, B, C are equal difference series, tolerance d = 3, a, B + 1, C + 6 are equal ratio series. Solving these three numbers needs solving process and thinking

a. If B and C are equal difference sequence with tolerance 3, then
a=b-3 c=b+3
a. If B + 1 and C + 6 are equal ratio sequence, then
(b+1)²=a(c+6)
(b+1)²=(b-3)(b+3+6)
After finishing, we get 4B = 28
b=7
a=b-3=7-3=4 c=b+3=7+3=10
a=4 b=7 c=10
The three numbers are 4, 7 and 10 in turn

If x + y = 0, xy = - 7, X2Y + XY2=______ ，x2+y2=______ ．

Solution; ∵ x + y = 0, xy = - 7 ∵ X2Y + XY2 = XY (x + y) = - 7 × 0 = 0x2 + y2 = (x + y) 2-2xy = 02-2 × (- 7) = 0 + 14 = 14

1. A and B start from a / B at the same time and run in opposite directions. If a starts a period of time ahead of schedule, the two vehicles will meet 30 minutes ahead of schedule. Given that a's speed is 60km / h and B's speed is 40km / h, how many minutes does a start ahead of schedule?
2. The distance between station a and station B is 360km. At the same time, the bus and truck start from station a and drive to station B. the bus runs 60km per hour, and the truck runs 40km per hour. After arriving at station B, the bus stops for 0.5h and returns to station a at the same speed. How many kilometers is the meeting place from station B?
There should be a process, not a lot of words. It's better not to mix words with arithmetic process (put them in a row). I'm confused

1. Method 1. Equation method: suppose that the time taken by two cars to complete a and B together is x, when a is ahead of Y, there are, (60 + 40) x = 60 [y + (X-30)] + 40 (X-30), y = 50. Method 2. The distance that a takes in advance = the distance that a and B walk together for 30 minutes, then the time that a takes in advance is 30 (60 + 40) / 60 = 502

A set of formulas arranged according to the law: the third power of X / y, the fifth power of - X / the second power of Y, the seventh power of X / the fourth power of Y, the ninth power of - X / the eighth power of Y
(XY is not equal to 0), where the sixth formula is --, and the nth formula is -- (n is a positive integer)

The observation shows that the molecule is (- x) ^ (2n + 1) = - x ^ (2n + 1)
The denominator is y ^ (2n)
So the sixth equation - x ^ 13 / y ^ 12
The nth formula is - x ^ (2n + 1) / y ^ (2n)

If - 1 / 2

From the meaning of the title,
（x+1/2）（2-x）>0
-x^2+3x/2+1>0
That is - 2x ^ 2 + 3x + 2 > 0
a=-2,b=3
[questions are welcome]

Pay attention to type up a clear picture quickly
I didn't take my exercise book home
I'll give 100 points and add it

However, we know that:
Hatred, even to the meaner,
It can also distort appearance
Anger, even anger at injustice
It can also make the voice hoarse. Ah, we are
People who want to lay the foundation for friendliness

First line: - 1 second line: 2 - 3 4 third line: - 5 6 - 7 8 - 9 fourth line: 10 - 11 12 - 13 14 - 15 16 Follow the rules
Line 10 from the left. What's the ninth number?

The answer is 90, each line has two more numbers than the previous line, so the ninth line is 1 + 2 * (9-1) = 17. That is to say, there are 17 numbers in the ninth line, from the first line to the ninth line, a total of (1 + 17) * 9% 2 = 81, so the last number in the ninth line is 81 (may be negative), so the ninth number in the tenth line is 81 + 9 = 90 (may be