What is the limit in mathematics? How to calculate the continuity of function? What is derivative? How to calculate

What is the limit in mathematics? How to calculate the continuity of function? What is derivative? How to calculate

Limit means that when an unknown quantity approaches a certain value, the original formula tends to a specific value to calculate the limit. First, find the unknown quantity to approach. If the unknown quantity can be eliminated, then eliminate it. If not, transform the formula into Infinitesimal Substitution or important limit formula. In a word, it is necessary to eliminate the single unknown quantity (when it approaches zero) or when the unknown quantity is equal to the approaching value

How to judge the maximum and minimum of function with derivative? What is stationary point?
Specific steps are required

The point where the derivative of a function is 0 is called the stagnation point of a function
Then, according to the stationary point, the extremum of the function can be determined
Then, compare all the extreme points, as well as the endpoint (closed interval), you can get the maximum!
The determination of the extreme point is as follows
If left increases and right decreases, then the stationary point is a maximum point and its function value has a chance to become the maximum;
If left decreases and right increases, then the stationary point is a minimum point and its function value has a chance to become a minimum
This is a bit like the list from high school
x xa
f’ 0
F minus minimum increasing

Given the plane vector a = (x1, Y1), B = (X2, Y2), if the module of a = 2, the module of B = 3, and the vector a point B = - 6, find (x1 + Y1 / (x2 + Y2)

-2/3

If the coordinates x and y of point P (x, y) satisfy xy = 0, try to determine the position of point P on the coordinate plane

When x = 0, the point is on the y-axis; when y = 0, the point is on the x-axis; when x = 0, the point is on the origin; when x = 0, y = 0, the point is on the origin

Where are the oral arithmetic problems of the second grade of primary school?

Elementary school mathematics volume 2 oral arithmetic
Time: 3 minutes
24÷4= 7＋63= 9×4= 36÷6= 9×7=
56÷8= 28＋6= 7×5= 36＋4= 30÷5=
63÷9= 64÷8= 38＋16= 45÷5= 7÷1=
25＋23= 12＋35= 27＋71= 46＋33= 40÷8=
21＋15= 36＋22= 59＋18= 72＋24= 41－29=
44－9= 72＋16= 43＋32= 35－8= 56÷7=
8×2= 7＋56= 56÷7= 12÷6= 4×2=
21－7= 7×3= 8÷8= 32÷4= 80－9=
( )×6=30 42÷7= 35－6= 28÷7= ( )×8=48
21÷3= 36÷4= 18÷2= 63÷7= 9×6=
9×9= 46＋10= 65＋40= 81÷9= 55－20=
9＋46= 9÷3= 9÷9= 58＋32= 80－28=
33＋60= 54÷6= 40÷8= （ ）×4=20 61－13=
15÷5= 9×3= 42－15= 18÷9= 180－60=
72－40= 47＋8= 14＋85= 61＋27= 170＋20=
5×9= 7×7= 73＋16= 60＋300= 10÷5=
83－29= 5×6= 43－17= 21＋27= 32÷8=
30÷6= 36÷4= 64÷8= 5÷1= 15÷3=
16÷8= 42÷6= 400＋50= 38＋26= 93－8=
49÷7= 6×9= 56－30= 35÷5= 27＋25=

It is known that the sum of solutions X and y of the system of equations x + 3Y = 2-5A and X-Y = 2A is negative, and a is the smallest positive integer that meets the condition

X+3Y=2-5a
X-Y=2a
Add the two expressions to get the
2X+2Y=2-3a
Divide both sides by two at the same time to get
X+Y=1-1.5a
The sum of X and Y is negative,
Then 1-1.5a2/3
Then the minimum positive integer a is 1
Then the inequality is X

Use 0, 3, 5, 7 and 9 to form the multiplication formula of three digit by two digit

Arrange yourself
Total 120-24-2 = 94 formulas

It is known that the hyperbolic equation is x ^ 2-y ^ 2 / 2 = 1, passing through point a (0,1) as a straight line with a slope of K (k is not equal to 0), and the straight line intersects the hyperbola at points P1 and P2. If the midpoint of p1p2 is on the straight line x = 1 / 2, the value of K is obtained

1

A math problem. Compare the size
M:(x^2-1)(x^2+x+1)-x(x^3+x^2-1)+5
N：（2x-7）（3x+8）-x（6x-5）+55
Compare the size of M and n

A: through simplification, M = - 1 + 5 = 4, n = - 56 + 55 = - 1, that is, M > n

The quadratic equation AX2 + BX + C = 0 has a root of 0 if ()
A. a=0
B. A is not equal to 0
C. B = 0 or a is not equal to 0
D. C = 0 or a is not equal to 0

x=0
Then 0 + 0 + C = 0
c=0
Then a ≠ 0
Choose D