Urgent. Math problems in the first year of junior high school. The faster you chase the score.

1) Prove congruence by using the corner edges, dac+ acd=90°, and acd+ bce=180°- acb=90°, so there is dac= bce, and both triangles are right-angled triangles, therefore, the other acute angle is also equal, plus the side ac=bc, so adc ceb

From the above two triangles congruence, then there is ad=ce, dc=be, so de=dc+ce=ad+be

2) The same principle, the same method first proves ADC CEB, then there is AD=CE, CD=BE, then there is DE=CE-CD=AD-BE

3) be=de+ad, the same way to prove adc ceb first, then there is be=cd=ce+de, and ce=ad, then there is be=ad+de

1) Proof of: dac+ acd=90°, acd+ ecb=90°, dac= ecb, ac=bc, adc= ceb=90°, acd cbe,ad=ce,cd=be,de=ce+cd=ad+be;

2) Solution: ed=|ad-be|．

When rotated around point c to the position of Figure 2, ed=ad-be;

When rotated around point c to the position of Figure 3, ed=be-ad;

When rotating around point C perpendicular to ab, de=be-ad=0, and the above is combined: ed=|ad-be|．

1) Because acd+ cad=90, acd+ bce=90, cad= bce, and because ac=bcADC= BEC=90 so δADC δCEB(AAS), so AD=CE, BE=CD, so DE=DC+CE=AD+BE

2) At this time, there is also δADC δceb(AAS), so AD=CE, BE=CD, so DE=CE-CD=AD-BE

3)de=be-ad

At this time there is also δADC δceb(AAS), so AD=CE, BE=CD, so DE=CD-CE=BE-AD

When x = 2, the value of ax to the fifth power + bx to the third power + cx-5 is 8, then ax to the fifth power + bx to the third power + cx = 13

When x = -2, the polynomial = -ax to the fifth power - bx to the third power - cx-5

ax to the fifth power + bx to the third power + cx) -5

Bring in specific values.

Discover patterns. Make up a knowing whole.

Know-18

Xiao Ming's father rode a bicycle with Xiao Ming on the highway at a constant speed, when Xiao Ming noticed the number on the roadside milestone for the first time, he found that it was a two-digit number and the sum of its two numbers was 9, just after an hour, he found that the number on the roadside milestone happened to be the first time he saw the single digit and the ten-digit number reversed, and after another 3 hours, he found that the number on the milestone was more than 0 in the middle of the two-digit number he saw for the first time, do you know what is the speed of Xiao Ming's father riding a motorcycle?

Solution: 1) Use the formula containing x and y to represent (x ten y) the first notice of a roadside milestone.

When the number is seen, what is the sum of the two digits of these two digits (x+y = 9) After an hour, he finds that the number on the roadside milestone is (10x+y) Another 3 hours have passed, and he finds that the milestone number is (100y+x) From the second time he saw the number on the milestone to the first time he saw the number on the milestone he traveled was (10x+y-x-10y), and from the third time he saw the number to the second time he saw the number, he traveled (100y+x-10x-y), the relationship between the two distances is (1:3).

2) According to the question, list the corresponding equation as ().

x+y =9

10x+y-x-10y):(100y+x-10x-y)=1:33)

x=7y=2

4) Calculate the speed at which Daddy rides a motorcycle is (45).

Write out the process in full, and understand it in detail!

Points are not a problem, some are points.

By the way, the following formula is simplified.

x+2)(x-2)+(x-2) +(x-2) quadratic +(x-4)(x-1)x-4+x -4x+4+x -5x+4

3x²-9x+4

No solution, you girl, do you know what the speed of Xiao Ming's father is on a motorcycle?

Xiao Ming's father rode a bicycle and took Xiao Ming to drive at a constant speed on the road

Simplify. x+2)(x-2)+(x-2) to the second power of +(x-4)(x-1).

x quadratic - 4 + x quadratic - 4x + 4 + x quadratic - 5x+4

3 x quadratic - 9x+4

A and B are 400 kilometers apart, and a slow train leaves A and travels 60 kilometers per hour; An express train departs from place B and travels 80 kilometers per hour. (1) Two trains go out at the same time, go in the opposite direction, and meet later, according to the conditions, the equation can be listed as 60x+80x=400; (2) when the slow train first drives out of 1, goes in the opposite direction, and when the fast train drives out, the two cars meet, then the equation can be listed according to the condition is 60x+80x=400-60; (3) If two cars drive out at the same time and go in the same direction, the fast train is behind the slow train, and the fast train catches up with the slow train, then the equation listed according to the condition is 60x+400=80x; (4) If two cars drive out at the same time, in the same direction, the slow train is behind the fast train, and the fast car is 640 kilometers apart, then the equation listed according to the condition is 80x+400-60x=640.

, B is 400 kilometers apart, and a slow train departs from A and travels 60 kilometers per hour; An express train departs from place B and travels 80 kilometers per hour.

1) Two trains depart at the same time, go in opposite directions, and meet each other at a time, according to the conditions, the equation can be listed as (60+80)*x=400

2) when the slow train first drives out of 1, it goes in the opposite direction, and when the fast train drives out and the two cars meet, then the equation can be listed according to the condition is (60 + 80) x = 400-60

3) If two cars drive out at the same time, going in the same direction, the fast train is behind the slow train, and then the fast train catches up with the slow train, then the equation listed according to the condition is (80-60)*x=400;

4) If two cars drive out at the same time, in the same direction, the slow train is behind the fast train, and the fast train is 640 kilometers apart, then the equation listed according to the conditions (80-60)*x=640-400

lz to put a little more thought, in fact, algebra is simpler than geometry Good luck with you

To be honest, I'm under a lot of pressure.

1 60x+80x=400

2 60（x+1）+80x=400

3 This question does not conform to the facts: slow train and fast train at the same time, fast train cannot be behind slow train, far-fetched point is listed as 60x=80x

4 80x-60x=640

The equation for (1) is (60+80)x=400, the equation for x=(2) is 60(1+x)+80x=400, and x=(3) is missing a condition, and the equation for 4) is 80x-60x=640 and x=32

1 (60+80)x=400

2 (60+ 80)x=400-60

3 (80-60)x=400

4？？？What are you asking for?

ab a total of 400km how do you get out of 640???

1. Non-positive rational numbers include (negative rational numbers) and (zero), and non-negative rational numbers include (positive rational numbers) and (zero).

2. Which of the following statements is incorrect about negative?

a, is a negative number and is not an integer b, is a fraction and not a natural number c, is a rational number and is not a fraction d, is a negative rational number and is a negative fraction.

Election C three, about the negative, which of the following statements is correct?

a, is a negative number and is not a fraction b, is not a fraction is a rational number c, is a negative number is also a fraction d, is a fraction is not a rational number.

Option C 4. Which of the following statements is correct?

a, positive integers, negative integers are collectively called integers b, positive fractions, negative fractions are collectively called fractions c, zero is both positive and negative integers d, rational numbers are a collective term for positive and negative numbers.

The largest negative integer is -1, the smallest positive integer is 1, positive rational numbers and zero are called non-negative rational numbers, and negative rational numbers and zero are called non-positive rational numbers.

6. Are all decimals not rational?

Both finite decimals and infinite cyclic decimals are rational numbers, and only infinite non-cyclic decimals are irrational numbers.

1. Zero, negative rational numbers. Zero, positive rational numbers.

II, C, III, C

Fourth, b5, non-negative rational numbers. Non-positive rational numbers.

Sixth, it is not.

1.0 Negative Rational Number 0 Positive Rational Number.

2. c3. c

4. b5.-1 1 Non-negative rational number Non-positive rational number.

6.No.

1) From the question, we can see that a-3=0

b-4=0c=0

a=3b=4

c=0, so a+b+c=3+4+0=7

2) Because a, b are the opposite of each other, so a+b=0 because c,d are the first and last countdowns of each other, so c*d=1

Since the absolute value of x is equal to 2, x = +-2

So: x 2-(a+b+cd)+(a+b) 2002+(cd) 2003