On the system of linear inequalities of one variable in the second grade of junior high school mathematics Give a basket of oranges to several children. If each child gets 4 oranges, there will be 9 oranges left. If each child gets 6 oranges, the last child gets less than 3 oranges. How many oranges are there?

On the system of linear inequalities of one variable in the second grade of junior high school mathematics Give a basket of oranges to several children. If each child gets 4 oranges, there will be 9 oranges left. If each child gets 6 oranges, the last child gets less than 3 oranges. How many oranges are there?

If there are x children, there are (4x + 9) oranges
(4x+9)-6x0
The solution is: x > 3
x

A rectangular floor is 6m long and 4m wide. It is planned to use blue and white square tiles. The side length of the blue brick is 20cm, and the unit price is 3 yuan. The side length of the white brick is 40cm, and the unit price is 8 yuan
(1) If x white bricks are purchased, and the total amount of floor tiles purchased is y yuan, please write down the functional relationship between Y and X;
(2) If the blue area of the floor after paving the floor tiles accounts for 1 / 3 to 1 / 2 of the total area, then what should be the total amount of floor tiles?

1) The area of blue brick is 0.04m^
White brick area 0.16m^
Buy x white bricks
Then buy blue brick (6 * 4-0.16x) / 0.04 = 600-4x
The total area is 24
White brick 0.16x
Blue brick paved 24-0.16x
y=8x+3(600-4x)=1800-4x
2) 24/3

If - 1 ≤ x ≤ 1,2x < A has a solution, then what condition must a satisfy

﹣1≤x≤1,2x＜a
﹣1≤x≠ 0
2x＜a a≥-2
x=0,a=0
x≤1 a≥2
If - 1 ≤ x ≤ 1, 2x < A has a solution, then a must satisfy a ≥ - 2

A group of students take a group photo at the school gate. It is known that it costs 0.6 yuan to develop a negative film and 0.4 yuan to develop a photo. Everyone gets a photo, and the average share of each person is not more than 0.5 yuan. How many students will take the group photo?

There are at least X students participating in the group photo, according to the meaning of the question: 0.6 + 0.4xx ≤ 0.5, ∵ x is a positive integer, ∵ 0.6 + 0.4x ≤ 0.5x, the solution is: X ≥ 6, answer: there are at least 6 students participating in the group photo

Solving logarithmic equation 4 ^ x ^ 2 * 2 ^ 7x = 16
^The sign here refers to the root sign
two
x 7x
4 * 2 =16
It's about this equation

4^x^2*2^7x=16
2^(2x^2+7x)=2^4
2x^2+7x=4
2x^2+7x-4=0
(2x-1)(x+4)=0
x1=1/2,x2=-4

The side length of the square is 20 cm, the area of the painted part
Picture 1: there is a circle in the painted square
Picture 2: there are two circles in the painted square
Picture 3: there are three circles in the painted square
Hurry up!

First: subtract the area of a circle from the area of a square to get 400-100 π square centimeters
The second one: how can the third two circles stay? Describe clearly

Huatuan brocade is restless
Connect () shoulder gale () field shortage ()
Head () dazzled not () of the land () but if lost

The flowers are in full bloom and are in constant flow
One after another, the wind howls, the field is desolate
Dizziness, barren land, loss

If the polynomial 2x ^ n - (M + n) x + 2 is a cubic binomial, then Mn=

n=3
m+n=0
∴m=-3
n=3
∴mn=-9

The number of real roots of equation x = 10sinx is——

The figure is a little rough & nbsp; the horizontal and vertical axes are out of proportion & nbsp; but the trend is probably right & nbsp; first draw the image of y = 10sinx & nbsp; wave peak value is 10 & nbsp; and then draw a straight line y = x & nbsp; must pass the point (10,10) & nbsp; as long as you find the position of this point and connect with the origin & nbsp; you can see the intersection point (marked by red circle) because there are three solutions when X & gt; 0 & nbsp; from the symmetry, you can see the left X & lt; 0 also has three solutions & nbsp; plus one solution at the origin & nbsp; so there are seven solutions & nbsp; to make it clear & nbsp;
By the way & nbsp; click to see a larger picture

1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1
The correct answer is 1 / 1 * 2 + 1 / 2 * 3 + 1 / 3 * 4 + 1 / 4 * 5 + 1 / 5 * 6 + 1 / 6 * 7

1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=6/7
Because 1 / 1 * 2 = 1-1 / 2