Given the function f (x) = x equal square - (A-2) x = a first: the equation f (x) = a about X second: the inequality f (x) = a about X third: if the equation f (x) = 0 has

Given the function f (x) = x equal square - (A-2) x = a first: the equation f (x) = a about X second: the inequality f (x) = a about X third: if the equation f (x) = 0 has

The first is the equation f (x) = a about X
X ^ 2 - (A-2) x = a, the solution is x = {(A-2) ± √ [(A-2) ^ 2 + 4A]} / 2
The second inequality f (x) = a about X, that is x ^ 2 - (A-2) x ≠ a, the solution is: X ≠ {(A-2) ± √ [(A-2) ^ 2 + 4A]} / 2
Third: if the equation f (x) = 0 has a = 0, that is, x ^ 2 + 2x = 0, the solution is x = 0 or x = - 2

First simplify and then evaluate (A-1) / (a2-2a + 1) + (a + 1) / (A2-1), where a = 2
Come on!

=(a-1)/(a-1)^2 +(a+1)/(a+1)(a-1) //
=1/(a-1) + 1/(a-1)
=2/(a-1)
=2 / (2-1) substituting a = 2
=2

As shown in Figure 1, in RT △ ABC, ∠ C = 90 °, D and E are the midpoint of AC and ab respectively, and point F is a point on the line segment CD. Fold △ ade along De to the position of △ a1de, making a1f ⊥ CD, as shown in Figure 2. (1) verify: de ∥ plane a1cb; (2) verify: a1f ⊥ be; (3) whether there is a point Q on the line segment A1B, making A1C ⊥ plane DEQ? Give reasons

(1) (2) AC ⊥ BC and de ⊥ BC, de ⊥ AC, ⊥ de ⊥ a1d, de ⊥ CD, ⊥ de ⊥ a1dc, a1f ⊂ a1dc, ⊥ de ⊥ a1f, a1f ⊥ CD, ⊥ a1f ⊥ B

What's the ratio of 17 percent to 40 percent?

17 / 40 = 17:40 = 42.5%

A key middle school in a city has built a rectangular playground with an area of 10800 square meters. The ratio of length to width is 4:3

Because the ratio of length to width is 4:3
So we can set length = 4x meters and width = 3x meters
Because the area is 10800 square meters
So there are
4X*3X＝10800
therefore
12X^2＝10800
therefore
X^2=900
therefore
X = 30 (m)
So 4x = 120 meters, 3x = 90 meters
Therefore, the perimeter of the rectangular playground is 2 * (120 + 90) = 420 (m)
For reference! Jswyc

Given that an acute angle of a right triangle is 60 ° and the length of the hypotenuse is 1, then the perimeter of the right triangle is ()
A. 52B. 3C. 3+2D. 3+32

As shown in the figure, in RT △ ABC, ∠ B = 60 °, ab = 1, then ∠ a = 90 ° - 60 ° = 30 °, so BC = 12ab = 12 × 1 = 12, AC = AB2 − BC2 = 12 − (12) 2 = 32, so the perimeter of the triangle is 3 + 32

Given that X and y are real numbers, please compare the size of x-2y + 3 and 2x-y square

Because (X & # 178; - 2Y + 3) - (2x-y & # 178;) = x & # 178; - 2x + 1 + Y & # 178; - 2Y + 1 + 1 = (x-1) & # 178; + (Y-1) & # 178; + 1 > 0
So x & # 178; - 2Y + 3 > 2x-y & # 178;

The shadow of a flagpole's top a falls on the slope d with a slope angle of 30 degrees. BC = 10m, CD = 8m and ADC = 60 degrees are known. Find the height of flagpole ab

Passing point D is de ⊥ AB, passing point C is CF ⊥ De
If the quadrilateral BCFE is a rectangle, then EF = BC = 10, be = CF, ∠ CDE = 30 degree
∴∠ADE=∠ADC-∠CDE=30°
In RT △ CDF, ∵ CD = 8, ∠ CDF = 30 °
Ψ CF = 4, DF = 4, radical 3
Be = CF = 4, de = EF + DF = 10 + 4, radical 3
In RT △ ade, ∵ de = 10 + 4, radical 3, ∠ ade = 30 °
Ψ AE = 10 radical 3 / 3 + 4
｜ AB = AE + be = 8 + 10 radical 3 / 3

Second grade primary school scientific inventions and small production, good is simple, materials can be seen everywhere

1. Start making small sailboats
Materials: prepare an empty bottle, a chopstick, two long strips of cardboard, several pieces of thick paper, a colored rope, adhesive tape and scissors
First of all, cut off the mouth of the empty bottle
2. Cut the bottle vertically
3. Next, stick two pieces of cardboard on the inside of the bottle
4. Cut one side of the thick paper into a bevel
5. Then, one by one stick on the top of chopsticks for sail
6. Tie the colorful rope on the top of the chopsticks
7. Stick the lower end of the chopsticks on the cardboard
8. Finally, tighten the color rope to both ends of the bottle body and stick it well
9. A sailboat is ready
Tips: in the process of making, every part must be firmly glued. The colored rope must be tight and firmly glued to make the hull balanced, otherwise, it is difficult for the sailboat to stand stably
2. Homemade Soap paper
Manufacturing materials and tools:
White paper with good hygroscopicity, small soap, a brush and disposable beverage can
Production method:
First, cut the soap into pieces and put it in a jar. Then put the cup on the stove and heat it. When the soap melts, cut the white paper into matchbox size, coat it with soap one by one, and then take it out and dry it in the shade
3. Homemade hot air balloon
1. First, we use soft paper to cut 6-8 leaves
2. Fold them in half and glue their sides together to make a balloon
3. Glue the four wires to the bottom of the balloon with adhesive tape. Fix the other end of the wires on the table with rubber paste
4. Adjust the speed of the hair dryer as slowly as possible. Align the air dryer mouth up to the bottom opening and turn on the switch. The balloon will slowly grow larger, tighten the thin line and leave the table

Given that (x-3) (x + 4) of 5x-1 = x-3 of a + X + 4 of B, find the value of a and B

a/(x-3)+b/(x+4) =[a(x+4)+b(x-3)]/[(x-3)(x+4)] =[(a+b)x+(4a-3b)]/[(x-3)(x+4)] =(5x-1)/[(x-3)(x+4)] a+b=5 4a-3b=-1 a=2,b=3