Story books are 1 / 4 more than picture books, story books are [], picture books and story books are []

Story books are 1 / 4 more than picture books, story books are [], picture books and story books are []

Story books are (1 + 1 / 4) △ 1 = 5 / 4 of picture books
The ratio of picture book and story book is 1: (1 + 1 / 4) = 4:5
A: story books are 1 / 4 more than picture books, story books are 5 / 4 of picture books, and the ratio of picture books to story books is 4:5

Congcong read a story book, 120 pages in the first week, 130 pages in the second week, three fifths of the book in two weeks
Q: how many pages are there in this story book? How many parts are left?
It's urgent, please ~ (≥ ▽≤)/~
Can we get rid of it by tomorrow?

(120 + 130) divided by 5 / 3 - (120 + 130) = 1250-250 / 3 = 500 / 3, of which 1250 / 3 is the total number of pages and 500 / 3 is the remaining number of pages

Why is the phase difference between voltage and current less than 90 degrees
The condition is: capacitive reactance equals resistance, inductive reactance equals resistance

Because the phase difference between the voltage and current at both ends of the capacitor is 90 degrees (current lead), the phase difference between the voltage and current at both ends of the inductor is 90 degrees (current lag), and the phase of the voltage and current at both ends of the resistor is the same. When the resistor and inductor or or capacitor are in series, the total phase is the vector sum of their respective phases, so the total phase difference must be greater than 0 ° and less than 90 °, This is true whether the capacitive reactance and inductive reactance are equal to the resistance or not

The school organizes tourism and rents cars. The number of people in these six classes is between 45 and 50. If you rent some 40 seat buses, there are 10 people without seats
If you rent a number of buses with 50 seats, 10 seats will be empty
1. How many people are there in this activity?
2. The rent of a 40 seat bus is 150 yuan per day, and that of a 50 seat bus is 180 yuan per day. How can we save the most?

290
One for 40 seats, five for 50 seats

Let a be a symmetric matrix of third order, and satisfy a & # 178; + 3A = 0, and the rank of a is known to be 2. Let's ask: when k is a value, the matrix A + Ke is a positive definite matrix
Hurry

A²+3A=0
So a (a + 3e) = 0, so a has only eigenvalues 0 and - 3,
Because R (a) = 2
So the eigenvalues of a are - 3, - 3,0
The eigenvalues of a + Ke are K-3, K-3, K-3
A + Ke is positive definite if and only if its eigenvalues are greater than zero
So when k > 3, a + Ke is a positive definite matrix
Note: it is proved that dependency A is a real symmetric matrix of order 3

How to calculate the sign of the power?
Especially with or without brackets

(- 2) &# 179; denotes that three - 2 are multiplied by (- 2) × (- 2) × (- 2) = - 8, and the odd power of negative number is negative
-2 & # 179; denotes the opposite number of three 2's Multiplication - 2 × 2 × 2 = - 2, the power first and then the sign (minus sign)
(- 2) &# 178; denotes that two - 2 multiply (- 2) × (- 2) = 4, and the even power of negative number is positive
-2 & # 178; denotes the opposite number of multiplication of two two - 2 × 2 = - 2, the power first and then the sign (negative sign)

Three teachers will take 38 students from class 4 (1) to visit the science and Technology Museum. There are two kinds of vehicles available for rent: one is minivan, which can take up to seven people, and the other is Xiaoqiao
It can take four people. Please write three different rent plans

1. 3 minibuses and 5 cars
It's a kind of full seat
Can the car not be full
Or the title is wrong
Formula: Set x minibuses and Y cars
7x+4y=41
y=(41-7x)/4
Self generation

LIM ((2x-1) / (3x-1)) ^ 1 / X (x → 0)

(2x-1)/(3x-1)=1-x/(3x-1)
When X - > 0, 1-x / (3x-1) ~ 1 + X
So the answer to the original question is natural logarithm base E

It is known that f (x) is an odd function defined on R. if the minimum positive period of F (x) is 3, f (1) > 0, f (2) = 2m − 3M + 1, then the value range of M is ()
A. M ＜ 32B. M ＜ 32 and m ≠ 1C. − 1 ＜ m ＜ 32D. M ＞ 32 or m ＜ - 1

Because f (x) is an odd function defined on R, and the minimum positive period of F (x) is 3, so f (2) = f (2-3) = f (- 1) = - f (1), and because f (1) > 0, so - f (1) < 0, that is, f (2) = 2m − 3M + 1 < 0, the solution is: − 1 < m < 32

OK, I see. How to say it in English?

OK, I see.