1. In known quadrilateral ABCD, AD / / BC, angle ABC = 80, angle BCD = 50, BC = 8cm 2. Two 12cm long segments AB and CD intersect at point O, and the angle AOD is 120. Try to judge the minimum value of segment AC + BD

1. In known quadrilateral ABCD, AD / / BC, angle ABC = 80, angle BCD = 50, BC = 8cm 2. Two 12cm long segments AB and CD intersect at point O, and the angle AOD is 120. Try to judge the minimum value of segment AC + BD

1. Make a parallel line of AB through point D and intersect BC at point E
∵ quadrilateral abed is parallelogram
∴AD=BE,AB=DE
∴AD+AB=BE+DE
∵∠DEC=∠ABC=80°,∠DCB=50°
∴∠EDC=50°
The EDC is an isosceles triangle, that is, ed = EC
∴BE+DE=BE+EC=BC=8cm

(column equation)
There is a temple in the mountain forest. I don't know how many monks there are in the temple, but I know there are 364 bowls. Three people eat a bowl of rice and four people drink a bowl of soup. They just use up the 364 bowls and ask how many monks there are in the temple
(write result step)
Open the pipe and inject water into the empty cylinder for 5 minutes. When it is full, pull out the bottom plug, and then the water in the cylinder can flow out in 10 minutes. When opening the pipe and injecting water into the empty cylinder, it took several minutes to find that the bottom plug was not plugged, so the bottom plug was immediately plugged, and it took the same amount of time for the water to fill up. Question: how long did it take to fill up the water tank?

There are x monks
Then
x/3+x/4=364
The solution is x = 624
Let's fill the tank with Tmin
1-(1/5-1/10)*t/2=1/5*t/2
Then t = 6.67min

Solving equation: 4x minus 16 = 0

4X minus 16 = 0
4x=16
x=16/4
x=4

Four fifths plus nine and five fifths plus ninety-nine and five fifths plus ninety-nine and five fifths plus ninety-nine and five fifths plus ninety-nine and nine hundred ninety-nine and five fifths

Four fifths plus nine and four fifths plus 99 and four fifths plus 999 and four fifths plus 9999 and four fifths plus 9999 and four fifths
=Four fifths + 9 + four fifths + 99 + four fifths + 999 + four fifths + 9999 + four fifths
=Four fifths × 5 + 9 + 99 + 999 + 9999
=4+9+99+999+9999
=(1+9)+(1+99)+(1+999)+(1+9999)
=10+100+1000+10000
=11110

Given that f (x) is a quadratic function, and f (0) = - 1, f (x + 1) = f (x) - 2x + 2, then the expression of F (x) is -- why

F (x) is a quadratic function, f (x) = ax ^ 2 + BX + CF (0) = - 1C = - 1F (x) = ax ^ 2 + bx-1f (x + 1) = f (x) - 2x + 2, substituting a (x + 1) ^ 2 + B (x + 1) - 1 = ax ^ 2 + bx-1-2x + 2aX ^ 2 + 2aX + A + BX + B-1 = ax ^ 2 + bx-1-2x + 22ax + A + B-1 = - 1-2x + 2 = - 2x-12a = - 2, a + B-1 = - 1A = - 1, B = 1F (x) = - x ^ 2 + X-1

The original price of a commodity is 200 yuan. After two price cuts, it's 160 yuan. It's known that the second price cut is 1 / 9. What's the first price cut?

The price after the first price reduction is 160 (1-1 / 9) = 180 yuan
So the first price reduction (200-180) △ 200 = 1 / 10
That is, 1 / 10 of the first price reduction

1. If the domain of F (x + 3) is {- 4.5}, then the domain of F (2x-3) is?
2. Given that the function f (x) satisfies the square of F (3x + 1) 9x - 6x + 5, then f (x)?
3. The definition field of function y = X-2 / 2 root 4-x is?
4. Function y = - x squared - 4x + 1, X belongs to {- 3.3} when the range is?

1 1＜x

I round to

I'm dizzy for you,

What is the percentage of the initial price of a commodity when the price is increased by 10% or decreased by 10% at the present price?

Just set it up
For example, 100 yuan for goods
Then after 10%, it will be 110
Another 10% is 110-11 = 99 yuan
So now it's the original 99%
The formula is (1 + 10%) (1-10%) / 1 = 0.99 is 99%

Given the square of a-4a + 1 = 0, find the value of the square of (A-1 / a)

a²+1=4a
Square on both sides
a^4+2a²+1=16a²
a^4+1=14a²
Divide both sides by a and 178;
a²+1/a²=14
(a-1/a)²
=a²-2+1/a²
=14-2
=12