My mother said to me, "I'm going on a business trip tomorrow, so you have to take care of yourself these days."

My mother said to me, "I'm going on a business trip tomorrow, so you have to take care of yourself these days."

Now it's imperative. After it's declarative, it should be related, not three clauses
My mother told me that I have to take care of myself these days because she is going on a business trip tomorrow
As a modal particle, it is necessary to delete it when the imperative sentence changes to the declarative sentence, because the subject of the speech changes and the modal particle of the original subject case can no longer be used

From 5x + 2 = 3x + 4, we get 5x + 3x = 2 + 4, from 2x-1 = 3x + 3, we get 2x-3x = 3-1
From 5x + 2 = 3x + 4, we get 5x + 3x = 2 + 4,
From 2x-1 = 3x + 3, we get 2x-3x = 3-1, right?

That's not right. First question x = 1

The center angle of the sector is 120 ° and the radius is 6cm. The surface area of the cone is

The side area is Pai * 6 ^ 2 * (120 / 360) = 12pai (cm ^ 2); the bottom radius is r = 6 * 120 / 360 = 2 (cm ^ 2); the bottom area is 4pai (cm ^ 2), so the surface area is 16pai (cm ^ 2)

Answers to page 40 of the guidance manual of Jiangsu Education Press
Let's talk about it if you know

Don't think about the answer, learning is down-to-earth, after three years of high school entrance examination you can get the answer? At this time, you can enrich your knowledge, lay the foundation for the high school entrance examination after three years, if you copy all the answers, you don't know how to think, you can't do well, knowledge is usually accumulated, not copy the answer

The problem of mathematical absolute value inequality
Solving inequality
（1）|x^2-x|x+1

1 first, X must be greater than 0, because the absolute value must be greater than or equal to 0. Then, when x is greater than or equal to 1 or less than or equal to 0, x ^ 2-x is greater than 0. Because less than 0 does not meet the conditions, the following step-by-step solution is omitted. If x > = 1, the absolute value sign is removed and becomes x ^ 2-x

The circumference of a semicircle is 10.28cm. Find its area

2TTR＝10.28
R＝5.14/TT
S＝TTR2
S= 26.4196/TT

In the cube abcd-a'b'c'd ', we prove plane acc'a ⊥ plane a'bd

Proof: ∵ AA '⊥ ABCD
∴AA'⊥BD
ABCD is a square
∴AC⊥BD
{BD ⊥ acc'a
Plane acc'a ⊥ plane a'bd

How to find the characteristic polynomial coefficient of matrix

The methods for finding the coefficients of the characteristic polynomial of matrix A are as follows:
1. The coefficient of characteristic polynomial of matrix A is the sum of all determinants at all levels
2. | λ e-A | expansion
Or by using the generalization of Weida's theorem
Find the root of | λ e-A | = 0
The coefficient of I power of λ is the sum of all the products of any I different roots. (I belongs to [0, n] and is an integer)

If the radius length r of a circle is 3cm, then the arc length I corresponding to the central angle of 36 degrees=____ Cm? Come on, today!

36*3.14*3/180=1.884cm

What are the first n-1 terms and formulas of arithmetic and proportional sequence?
It seems that n-1 can't be used to replace n in the first n terms and formula?

1. The sum formula of the first n terms of arithmetic sequence Sn = Na1 + n (n-1) d / 2
Then: the first n-1 term of the arithmetic sequence and the formula s (n-1) = (n-1) a1 + (n-1) (n-2) d / 2
2. The sum formula Sn = A1 × (1-Q ^ n) / (1-Q)
Then: the first n-1 term and formula s (n-1) = A1 × [1-Q ^ (n-1)] / (1-Q)