2. 1/( 1/8+ 1/ 12)= 4.8(h)
3. Let this number be x, and the difference with 15 is n times of 45, then
45n=x- 15
60(n- 1)=x
solve
x=240
Urgent! Math problems, online, etc! Pythagorean theorem, just draw it.
Solution: the bottom of the ladder will slide x meters.
2.5*2.5 (representing the square of 2.5, and so on)
2.5*2.5-0.7*0.7=5.76=2.4*2.4 (calculated by the wall length).
2.4-0.4 = 2- This is the distance after sliding.
2.5 * 2.5-2 * 2 = 0.7+x squared
6.25-4 = 2.25 =1.5 *1.5 = the square of (0.7+x).
X= 1.5-0.7=0.8，
Over. . . .
Look carefully and don't worry. . .
Pythagorean theorem is used twice, once before sliding and once after sliding. .
Understand? . . .
With a as the origin, AB as the x axis and AD as the y axis.
Let M(a, radical number 3)
Therefore, a*(4-a)- (radical number 3) 2 = 0 a = 1 or a=3.
Similarly, let N(b, 0) b= 1 or b=3.
So MN= root number 3 or MN= root number ((3- 1) 2+ (root number 3) 2) = root number 7.
Online class, math problems, urgent setting teacher X years old, students Y years old this year.
When the teacher was the same age as the student, it was (x-y) years ago, and the student was 3 years old before (x-y), so the equation y-(x-y)=3 was obtained.
When the student is as old as the teacher, it is (x-y) years later, and the teacher is 45 years later, so the equation x+(x-y) = 45.
Simultaneous equations are solved with X=3 1 and y= 17.
The teacher is 3 1 year old this year, and the students are 17 years old this year.
2^a*2^b*2^c*2^d=2^a+b+c+d
=5 12
=2^9
a+b+c+d=9
The mathematical problem on the emergency line (1) assumes that the planting area of corn is X mu, and the total sales price of three crops is Y yuan.
y=680x+650(5-x)+4000=7250+30x
(2) Four schemes
Wheat, corn and soybeans
5 1 4
5 2 3
5 3 2
5 4 1
(3) From (1), we know that the bigger X is, the bigger Y is, so we choose the fourth scheme with the highest price, 7370.
(4) Let the total profit be Z, then: Z = 7250+30x-1000-130x-50 (5-x) = 6000-50x.
So the bigger X is, the smaller Z is, so when X = 1, the maximum profit is 5950.
Eggplant 20 kg
Pepper 30 kg
Cucumber 40 kg
Pepper * * * appears twice, 1 time with cucumber and once with eggplant. Cucumber * * * weighs 70kg and eggplant weighs 50kg, so we should compare 70kg-50kg = 20kg, eggplant 50kg-20kg = 30kg and 70-30kg.
There are 4 people who don't like sports or music, 55-4 = 5 1, which means 5 1 people like at least one of music and sports.
5 1—43=8: It means that there are 43 sports lovers, and 5 1 person is interested in at least one of music and sports, so 8 people only like music.
Because there are 34 music lovers, subtracting 8 people who only like music equals 26 people, that is, the number of people who like sports and music in the class.
The first question: two answers.
1:3+3+4= 10
2:3+4+4= 1 1
The second question: an answer
9+9+4=22
Math problem, online urgent 1. 10X-X=28.8.
X=3.2
Mistake 3.2 yuan for 32 yuan.
2.88*88=7744
B=8
A=7
F=4
77*88=6776
C=6
55*99=5445
D=5
E=9
A+B+C+D+E+F equals 39.