A book is planned to be finished in 10 days, because it has 9 more pages per day. As a result, it has been finished in 8 days, and there are several pages in the book

Because I read 9 more pages every day, I finished it in 8 days
Read more 9 × 8 = 72 (page)
Read more 72 pages, originally to use (10 - 8), that is, two days to read
Therefore, the number of pages of this book is 72 × [(10-8) × 10] = 360 (pages)

When someone reads "one hundred thousand whys for primary school students", the ratio of the number of pages he has seen to the number of pages he has not seen is 1:5. If he reads another 20 pages, the number of pages he has seen accounts for 1 / 3 of the total number of pages. How many pages are there in "one hundred thousand whys for primary school students"?

20/(1/3-1/1+5)=120

[programming] input a four digit positive integer from the keyboard. First, separate each digit in the positive integer, and output each digit in reverse order
#include
#include
void main ()
{
\x09int a,b,c,d,x;
\X09printf ("please enter a four digit positive integer):";
\x09scanf("&d",x);
\x09if (x > 9999 || x < 1000)
{
\x09 printf("Input Error!\n");
\x09 exit(-1);
\x09}
\x09else
\x09{
\x09\x09a=x / 1000;
\x09\x09b=x / 100 % 10;
\x09\x09c=x / 10 % 10;
\x09\x09d=x % 10;
\x09}
\x09printf("The Inverse Number is ");
\x09scanf("%d",a + b * 10 + c * 100 + d * 1000);
}
What's wrong with this? Why is it always "input error"!

There are two mistakes. First, scanf() should read in the address of the variable, so scanf (& quot; & amp; D & quot;, x) should be scanf (& quot;% D & quot;, & amp; x) & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; / / if you want to use & amp; X, the program will make an error. Second, scanf (& quot;% d {

What is the Three Gorges

Three Gorges
From ancient to modern times, the Three Gorges, a magnificent grand canyon in the Yangtze River, is one of the ten great scenic spots in China. It rises from the white city of Fengjie County in Sichuan province to the south of Hubei, Yichang, and is composed of Qutang gorge, Wuxia gorge and Xiling gorge. The total length is 192 km, of which 90 km is the canyon.
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If a is the third order infinitesimal of X and B is the fourth order infinitesimal of X when x tends to 0, can we conclude that B is the infinitesimal of higher order than a?

If a is the third order infinitesimal of X and B is the fourth order infinitesimal of X when x tends to 0, then it can be concluded that B is the infinitesimal of higher order than a
Because of the following reasons:
f(x)=B/A,
When x tends to zero, the first, second, third and fourth derivatives of B to X are all zero,
The first, second and third derivatives of a to X are all 0, and the fourth derivative is not a non-zero value of 0,
Lim f (x) = B ^ ('4) / [a ^ ('3)] '= 0 / [nonzero] = 0,
It is concluded that B is infinitesimal of higher order than a

There are 50 students in class 5 (1), among which there are 8 Sanhao students?

8 / 50 = 4 / 25 the answer is that the number of Sanhao students accounts for 4 / 25 of the total number of students in the class

What is 1 / 30 + 2 / 30 + 3 / 30 +... + 28 / 30 + 29 / 30?

Correct answer: 14.5
Analysis:
The original formula = 1 / 30 * (1 + 2 + 3 + 4 + 5 + 6 +29+30)
=1/30*[(1+30)*30/2]
=1/30*465
=14.5
Tip: the solution can be obtained by using the method of raising common factor and the formula of summation of arithmetic sequence

In the arithmetic sequence with 2n + 1 terms, if the sum of all odd terms is 165 and the sum of all even terms is 150, then n is equal to ()
A. 9B. 10C. 11D. 12

From the odd number term and S1 = (n + 1) (a1 + A2N + 1) 2 = (n + 1) × 2An + 12 = (n + 1) an + 1 = 165, ① even number term and S2 = n (A2 + A2N) 2 = n × 2An + 12 = Nan + 1 = 150, ② n + 1n = 165150, the solution is n = 10

A person gets 240 yuan salary. There are 50 pieces of 2 yuan, 5 yuan and 10 yuan, of which 2 yuan and 5 yuan are the same number, then 10 yuan is the same number

Suppose there are x sheets for 10 yuan, then there are 25-0.5x sheets for 2 yuan and 5 yuan
10x＋〈2＋5〉×〈25－0.5x〉＝240
6.5x＝240－175
x＝10
A: 10 yuan, 10 sheets

Find the rule first, then fill in the number (1) 23, 1, 32, 94 、．

94 × 32 = 278; 278 × 32 = 8116

A book is planned to be finished in 10 days, because it has 9 more pages per day. As a result, it has been finished in 8 days, and there are several pages in the book