Say 3 math problems, give 100 points

1. 10 days 10mm

9 days 5mm

8 days 7 days. II. (Binary Linear Equations).

Set up male x people and female y people.

x+y=152………

1-1/11)x=y-5………

10 11x=y-5 is obtained by

y=10/11x+5………

Substitute for , get.

x+10/11x+5=152

21/11x=147

x=77 substitute x=77 into , get.

y=75x=77,y=75

There are 77 boys and 75 girls.

3. Set the length x cm and the width y cm.

2×（x+y）=20

x+y=10

Length cm Width cm Area c

There are 5 cases in total, with a maximum area of 25C

These are all written formats and can be written directly.

My answer is detailed enough, and it has reached the extreme.

Give it to me!!

So it takes 7 days to grow to millimeters.

2.There are x boys and 152-x girls.

10/11x=152-x-5

21/11x=147

x=77152-x=152-77=75

There are 77 boys. 75 girls.

3.Length, width, area.

The maximum area is 25

Question 1: 10 days.

8 = 2 * 2 * 2 (3 2's).

10-3 = 7 days.

So it takes 7 days.

Question 2: x+y=152

1-1/11)x=y-5

x=77,y=75

Question 3: There are 5 different types of enclosures.

Enclose a square: 5*5=25

Question 1: 8 = 2 * 2 * 2 (3 2's).

It takes 7 days to grow to millimeters.

2 2 2=, 10-3=7, 7 days.

2. According to the reasoning, boys can only be , etc., and it is inferred that there are 77 boys and 75 girls.

Column equation: Let the male student be x, then: x+10x 11+5=152 solve the equation to get x=77 people.

then girls = 152-77 = 75 people.

3. There is a side length is, 5, five kinds of circumference, the largest area is the circumference method with a side length of 5, 5, and the area is 25 square centimeters.

One: Because it doubles in one day. 9 days is 5mm; 8 days is; 7 days is so it is 7 days.

2: If there are x boys, then 152-x girls are girls.

1-1/11)x=152-x-5

Solution; x=77

Girls: 152-77=75

Three: Because it is a rectangle or a square.

So there are two sides equal.

The sum of two different sides = 20 2 = 10

So there are 5 kinds.

Let one side be x and the area be y

y=x*(10-x) gives the maximum when x=5.

5*5=25 square centimeters.

1 It takes 7 days.

2 77 boys and 75 girls.

3 There are 5 types of circumference (width 1, length 9; width 2, length 8; width 3, length 7; width 4, length 6; The side length is 5), and the area is up to 5 in the case of the side length 5, and the area is 25 square centimeters.

Sky. 2.There are 77 boys and 75 girls.

There are x boys and y girls.

x+y=152

x-1/11x=y-5

3.There are 5 types of enclosure methods, with a maximum area of 25 square centimeters.

Question 1. If it takes x days to grow to millimeters, isn't it (x+1) days to be long to millimeters? Similarly, it took (x+2) days to grow to 5 mm and (x+3) days to 10 mm. x+3=10，x=7.It takes 7 days.

Question 2. If there are x boys, then there are girls (152-x), and you can make equations! x-(1 11)x=(152-x)-5, and x=77 is solved, then 152-x=75 is 77 boys and 75 girls.

Question 3. First of all, you need to know that cubes are special cuboids! Let one side be long x, the other side is long (10-x), in order to avoid repetition, you may wish to set x<=(10-x), then x<=5, there is x can not get 0, x can get 1 5, there are 5 ways.

Enumerating the 5 methods, it can be seen that the maximum area is 5*5=25 square centimeters. It is also possible to use a quadratic equation, where the area s=x(10-x)=-(x-5) 2+25, and it is clear that s is maximum when x=5.

Question 1: Set the worm to be x mm

Question 2: Solution: Let the total number of boys be x, then x 11 is the total number of boys.

Let the total number of girls be y, so 125-x=y, and then the title says; The number of men and women is equal when these people are removed, so: x-x 11=y-5, x-x 11=10x 11, so: 10x 11=y-5, so: 10x 11=y-5,

7 days, 77 for men, 75 for women, 5 types, the maximum is 25

The insects are seven days, 77 males and 75 females, a total of 5 species: 1 92 83 74 65 5, the latter is the largest.

Question 1: 8 = 2 * 2 * 2 (3 2's).

It's 8 times longer, and 3 days less is fine.

It takes 7 days to grow to millimeters.

Question 2 x+y=152

x10/11=y-5

x=77 male.

y=75 female.

Question 3 Circumference 20, length + width = 10, 5 types.

x+y=10

Find 25 when the maximum value of xy is x=y

7 days Male 77 Female 75 5 types of squares are the largest in area of 25

Use a square piece of paper with a side length of 18 cm, cut and paste it into a rectangular carton without a lid, so that its volume is greater than 400 cubic centimeters.

1.The length of the made cuboid carton is (12

cm, width is (

12) cm, height is (3

Centimeter v = 3 * 12 * 12 = 432>400

1. The straight line y=-2 3*x-5, intersecting with the coordinate axis a(-15 2,0)b(0,-5).

At the same time, it can be calculated that b=-5

C(5 2,0) is obtained, so the area of the triangle ABC = 1 2*(5*15 2+5*5 2)=252, since Y=X-1 and the coordinate axis intersection coordinates A(1,0)(0,-1), the equation for the perpendicular bisector of the AB line is Y=-X, and the point C is on the Y axis, then C(0,0).

f(x) is a one-time function and at (1,+ is an increasing function, so the slope is positive.

i.e. 1 a>0

So a>0

The cube is equal to the equals.

The cuboid is 9*8 equal to 72

is the square difference of a and b and the above equation is equal to (a+b)*(a-b).

The speed ratio of car A and B is 4:3, and the time ratio is 3:4 for the same distance

It takes 7 hours for A to complete the journey, then B takes 7 3 * 4 = 28 3 hours, so 1 (1 7 + 3 28) = 4 hours after the two cars depart.

Let the first speed be 4V and the B speed be 3V

The total distance is 4V*7=28V

The time taken for the encounter is 28V (3V + 4V) = 4 hours.

If the range is r, then the true number takes all the positive numbers.

True number = (x -4x + a) x

If a>4

Then x -4x+a=(x-2) +a-4>0 true number is greater than 0, so the denominator x>0

Then the true number cannot take all the positive numbers.

a=4, then (x-2) x, can take all positive 00 zero points x=2 (4-a), x=0

Because 00 02+ (4-a).

That is, the denominator is greater than 0, and the numerator can take negative numbers without considering the defined domain, i.e., all positive numbers can be taken, so this is true.

So 0