2. Post the problem on the Internet and offer a reward for help;
3. Ask your math teacher or a master around you;
4. Decompose a difficult problem into several relatively basic small problems and break it into parts;
5. Learn basic formulas and questions well, check more relevant materials and think more about the combination of numbers and shapes.
6, this is not good, then leave it to your son, the son has grandchildren, the grandson has sons, and the descendants are infinite!
Ask everyone a math problem. I haven't thought of it for a long time. Laugh! 2 178
This is a math problem. I have been doing it for a long time, but there is no answer. Please help me set the original speed to xkm/h.
20 \4x+6/60 = 20 \x
X =150km/h
The original speed of the train is150km/h.
Physics problem, I haven't worked out the turn-off switch S3 for a long time, and when the switch S 1 is closed, the power consumed by the resistor R 1 is P 1 (this is R 1 and R3 in series).
When S3 is turned off and S2 is only turned on, the power consumed by resistor R2 is P2 (this is R2 and R3 in series).
P 1: P2 = 4: 3，R 1=3R2，
When the switches are all closed, the total power consumed by the circuit (which is the parallel connection of R 1 and R2) is 64W.
Found: (1) What is the resistance R2: R3?
(2) When S3 is off and S2 is on, what is the electric power consumed by resistor R3?
(1) U2/(r 1+R3): U2/(R2+R3) = (R2+R3): (r1+R3) = 4: 3 (R3 can be obtained by substituting the numerical relationship between R1and R2.
There is a math problem, please ask you. I haven't thought of it for a long time! Let the number of remaining b piles be x.
So armor and armor
3X to the left
Take 9X 9X away.
Total 12X 10X
Because pile A is more than pile B 18 tons.
So12x-10x =18.
2X= 18
X=9
So 9X=9*9=8 1.
So we ship 8 1 ton.
Math problem, if you can work it out, work it out! Acute isosceles: 14cm, 14cm, 1 1cm.
Let two waist lengths a and base b have a-b = 3 and 2a+b = 39, respectively, and solve them.
Oblique isosceles: 12cm, 12cm, 15cm.
Let two waist lengths a and base b have b-a = 3 and 2a+b = 39, and solve them.
A math problem, I thought for a long time but didn't come up with it! You are in Grade One, aren't you? It's simple. First of all, you should discuss it with odd numbers and even numbers. If there are odd machine tools, the middle 1 is p.
If it is an even number of machine tools, it is in the middle of the middle two (including these two).
The second problem is the geometric meaning based on absolute value. Draw a number axis, and this problem can be transformed into the sum of the distances between points corresponding to X and 1 2, ... and 6 17. Obviously, when x=3 14, the sum is the smallest (you can imagine that when x moves left and right, the distance between each number and it changes, that is, the sum of the distances between 1 and 6 17 is equal, and the distance between 2 and 6 16 is equal ... so there are only x and 3/6.
Forget it yourself. ...
20 points for success! A math y = 2x+k, y 2 = 4x.
y^2=(2x+k)^2=4x
4x^2+4kx+k^2=4x
4x^2+4(k- 1)x+k^2=0
Discriminant =16 (k-1) 2-16k2 =16 (2k-1) (-1) =-16 (.
k= 1/2
Solve this math problem? Urgent! I haven't come out for a long time! ( 1)、f(x)=(cosx/2+sinx/2)(cosx/2-sinx/2)+(-sinx/2)(2 cosx/2)
= cosine-sine
=v2cos(x+π/4)，
The minimum positive period T=2π/ 1=2π,
The monotone decreasing interval of cosx is [2kπ, 2kπ+π],
Therefore, the monotone decreasing interval of f(x) is [2kπ-π/4, 2kπ+3π/4];
(2)、f(x)= 1=v2cos(x+π/4)，
——《x+π/4 = 2kπ+-π/4，x∈[-π/2，π/2]，
-x =-π/2, or x=0,
——》x 1+x2=-π/2 .
Who wants to help me solve a math problem? Actually, I don't know.
But there is one person who will
It is your math teacher.
You ask him.