A math problem, teach me, thank you

It's 40 minutes.

You can set the original length to h, and after burning, the coarse one becomes 2y, and the thin one becomes y, and it stops for x hours.

The coarse one can be burned for 2 hours, after burning, 2y can be burned for 1 hour, and after burning, y can be burned for 1 hour, and after burning, y burns h-yh 2=(h-2y) x

h/1=(h-y)/x

h=3y means that the 1 3 length of the coarse candle was burned, which is 2 3 of 2 hours, and the 2 3 length of the thin candle was burned at the same time, which is 2 3 of 1 hour

It's 40 minutes.

The total length is 1 set for x hours of stopping.

Then the thick one has 1-x 2 left, and the short one has 1-x left, then 1-x 2=2 (1-x).

So x = 2 for 3 hours.

That's 40 minutes!

Solution: Coarse candles burn 1 120 per minute, thin candles burn 1 60 per minute, and there is a power outage for x minutes.

1-x/120=2×（1-x/60）

1-x/120=2-x/30

x/30-x/120=1

x/40=1

x = 40 minutes.

A: There was a power outage for 40 minutes.

A: 40 minutes.

Untie. Assuming that the bottom area of the thin root is s, then the thick one is 2s and then the volume of k is consumed per minute, and the power is cut out for t minutes.

1）120k=2sh

2）60k=sh

3) h-kt (2s) = 2 (h-kt s) substitution, and t = 40 min was solved.

Solution: Take the midpoint of the water surface as the origin point as the ordinate and abscissa respectively.

Throw off the line: y = -5/27 x square +

Substituting x=y=60/119 is less than so you can (because of the mobile phone, you can't write so detailed, you still look at the method).

Coarse candles consume 1 3 = 2 3 h

Thin candles consume 2 3 = 2 3 h

So the power went out for 40 minutes.

During the power outage, Xiao Ming lit two candles. The two candles are not as thick, but they are the same length. Coarse candles can be lit for 2 hours, and thin candles can be lit for 1 hour.

After the call, when Xiao Ming blew out the candle, he found that the remaining thick candle was exactly twice the length of the thin candle. Q: How long was the power outage?

Set the power outage xh, then 1-x 2 = 2 (1-x), 2-x = 4-4x, x = 2 3

Calculate a+b+c and then merge the same kind of terms, and see whether the result is a constant or only exists c, if so, Zhang Hua is right.

There's a simple algorithm: you see a=5a3 b+[[2a4]]]]3a2 b 2-ab 3+8

b=6ab^3-8a^2 b^2+【【3a^4】】】5b^4

c=5a^3b+【【5a^4】】】11a^2 b^2+5ab^3-5b^4

[[Inside, have you found it?] Is the parentheses in a+b equal to the ones in c? So it's Chen Cheng.

You put the algebraic formulas a+b+c and a+b-c in known algebraic expressions for the final finishing.

Then compare and get it. See whose value has nothing to do with a or b.

Solution: (1) Let the number of orange trees be increased to x, and the average number of oranges per fruit tree is yy=5x2)w=(60+x)(500-y)(60+x)(500-5x).

30000+200x-5x²

3）30000+200x-5x²=1500+60*500x²-40x+300=0

x-30)(x-10)=0

x1=30,x2=10

4)w=30000+200x-5x²

So when x=-200 -5*2=20.

wmax=32000

Liu Chang 123456liu, hello:

Cylinder diameter: 40 2 5 4 (Li Zhi Bi cm).

Cylindrical radius: 4 2 2 (centicoma meters).

Cylindrical volume: cubic centimeters).

Hello: de=2 times the root number 6

Analysis: In the triangle ABC, de BC, the triangle ADE is similar to the triangle ABC triangle ADE ratio quadrilateral BCED area ratio is 1:2, therefore, the triangle ADE to the triangle ABC area ratio is 1:

3 Basis: The area ratio in a similar triangle is the square of the side length ratio.

You can get: (de:bc) squared = 1:3

will"bc = 2 times root number 6"Substitution.

You can get: de=2 times the root number 6

Good luck!

Because de bc

So ade abc

s△ade:s△bced=1:2

s△ade:s△abc=1:3

The area ratio of a similar triangle is the square of the side length ratio.

So (de:bc) 2=1:3

3de^2=bc^2

bc=2√6

de^2=√8

de=2 2

BC=2 times the root number 6 is not practical, solution: because the S triangle Ade:S quadrilateral BCED=1:2, so SδAde:SδABC=SδAde:(Sδade+S quadrilateral BCED)=1:3

Because de bc

So δabc δade

So ae:ac=1:3

Because AC=AE+EC

So ae:ec=1:((3)-1).

Because the height of the triangle ADE is equal to the height of the triangle DEC.

So the area ratio is equal to the square of the base edge ratio.

So sδade:sδdec=1:4-2 3

A square multiplied by 5 equals 40, and a square equals 8. Do you need to ask?

A square is equal to 8, and a triangle is equal to 200 divided by 8 to equal 25ok

A square multiplied by 5 equals 40

Then the square is: 40 5=8

A triangle multiplied by a square equals 200

Then the triangle is: 200 8=25

The square is 8 and the triangle is 25

Solution: Stool slag rot according to the formula: nc(k-1)+nck=(n+1)ck, the original formula =(n+1)c0+(n+1)c1+(n+2)c2+....Jujube leaks....+(n+m-1)c(m-1)

n+2)c1+(n+2)c2+……n+m-1)c(m-1)(n+3)c2+…Liang Zheng....+(n+m-1)c(m-1)(n+m-1)c(m-2)+(n+m-1)c(m-1)(n+m)c(m-1)