1： The square of x minus the square of Y, the square of x plus the square of Y minus 2XY 2： The square of a minus the square of B the square of a plus the square of B minus 2A + 2B a-b

1. Square difference formula = (x + y) (X-Y) x ^ 2 + y ^ 2 - 2XY can be applied to square difference formula = (X-Y) ^ 2 (i.e. the square of (X-Y)) so that the upper and lower can be reduced. 2. Similarly, a ^ 2 - B ^ 2 = (a + b) (a-b) so that the denominator can be divided into

RELATED INFORMATIONS

1. In mathematics class, Mr. Zhang showed the question: as shown in the figure: △ ABC is an isosceles right triangle, ∠ ACB = 90 °, ab ⊥ BF, point P is any point on BC, and AP ⊥ PF. Is AP equal to PF? If "point P is any point on edge BC" is changed to "point P is any point on extension line of edge CB (except B and C)", other conditions remain unchanged, then is the conclusion still valid? If correct, please draw a graph and write the proof process
2. 1. There are two experimental fields of wheat with equal area. The first one uses the original variety, and the second one uses the new variety. 9 tons and 15 tons of wheat are harvested respectively. It is known that the average yield of the first experimental field is 3 tons less than that of the second one. The average yield of these two experimental fields per hectare is calculated respectively
3. Fill in the appropriate formula to make the following equation true a²-b²+2b-1=a²-（）² -x²+y²-2x-1=（）（） Write the result of factorization directly -2x²+4x-2=-2（）² If 1 / 3 of a + A is known, then the value of 1 / 178 of a + A is () Decomposition factor x²-3xy+2y² （x+y）²+2（x+y）-15
4. 1. If the root of equation 5 (x-1) = 3A + X-11 of X is nonnegative, then the value range of a is () 2. Given the linear function y = (M + 2) x - (M + 3), y decreases with the increase of X, and the intersection of image and Y axis is above X axis, then the value range of real number m is () 3. Given | 2x-24 | + (3x-y-k) * 2 = 0, then the value range of K is () 4. If the image of the first-order function y = 3x + M-1 does not pass through the second quadrant, find the value range of M () 5. If a ＞ 0, B ＜ 0, then the equation | x-a | + | X-B | = the range of a-b______ 6. Given that the solution set of inequality system {x + 2 ＞ m + N, X-1 ＜ M-1 is - 1 ＜ x ＜ 2, then (M = n) * 2008=_________ If necessary, why,
5. Some problems in Mathematics in grade two of junior high school 1. Without changing the value of the fraction, change the coefficients in the numerator and denominator of the following formulas into integers (1) (5 / 6 x) + y (2 / 3 x) minus (2 / 3 y) (2) (0.3A) - 2b of (0.7b) Calculate one question: - 2 ≤ one third (1-2x) < 1
6. On several mathematics problems in grade two of junior high school 1. For a project, team a will complete it in 40 days. If team B will complete it in 30 days, team a and team B will cooperate for another 20 days ① How many days does it take for engineering team B to do it alone ② The project is divided into two parts, one part of which takes X days, the other part takes y days, where XY is a positive integer and X is a positive integer
7. First question: The second power of (M + n) - the second power of 4N= Second question: The fourth power of X - the second power of 2x, the second power of Y + the fourth power of Y= Third question: The second power of 39.8-2 × 39.8 × 49.8 + 49.8= Fourth question: If the quadratic power of M - the quadratic power of n = 8, - M-N = - 4, then the value of M-N is
8. Forget the formula, mathematics always forget that forget this, what problem formula can't remember. Ah A method of solving equations is called formula method!
9. 3-square-1 = 1 * 8; 5-square-1 = 3 * 8; 7-square-1 = 6 * 8; why? ditto
10. 3's Square-1 = 8 * 1, 5's Square-1 = 8 * 3, 7's Square-1 = 8 * 6, 9's Square-1 = 8 * 10, find the rule
11. Find the answer to a math problem in grade two Given that m of n is equal to 5 of 3, find the value of (M / M + n) + (M / m-n) - (n ^ 2 / m ^ 2-N ^ 2) Additive process
12. It is known that: as shown in the figure, in the trapezoidal ABCD, ad ‖ BC, ad = 24cm, BC = 30cm, point P moves from point a to D at a speed of 1cm / s, and stops at point D. point Q moves from point C to B at a speed of 2cm / S, and stops at point B. the straight line PQ cuts the trapezoid into two quadrangles?
13. There is a triangular open space in the campus. Now we are going to plant turf on this open space to beautify the environment. We have measured its three side lengths of 13 meters, 14 meters and 15 meters respectively. If the price of this kind of turf is 120 yuan per square meter, how much will it cost to buy this kind of turf at least? So what? It's better to be complete
14. Given that the side length of square ABCD is 8, point m is on DC, DM is 2, and N is the first moving point on AC, then the minimum value of DN + Mn is? I know it's 10, but how can I get it? It's better to have a picture Also, I wish you a happy New Year's Day!
15. A meteorological research center observed the whole process of a sandstorm from its occurrence to its end. At the beginning, the wind speed increased by 2km / h on average. After 4h, the wind speed increased by 4km / h on average when the sandstorm passed through the open desert. For a period of time, the wind speed remained unchanged at 32km / h. When the sandstorm met the green vegetation area, the wind speed decreased by 1km / h on average. At 40H, the measured wind speed was 17km / h According to the images of wind speed and time, the following questions are answered: (1) fill in the corresponding values in the y-axis (); (2) how many hours have the sandstorm passed from the occurrence to the end? (3) The functional relationship between wind speed y (km / h) and time x (H) is obtained when x ≥ 4
16. Nanxun ancient town is a famous tourist attraction in China. Here is a passage about the charging standard between a school team and a tour guide of a travel agency Leader: how much is the charge for a tour to Nanxun? Tour guide: if the number of people does not exceed 30, the per capita travel cost is 360 yuan Leader: if more than 30 people, how to get a discount? Tour guide: if there are more than 30 people, the per capita travel expenses will be reduced by 5 yuan for each additional person, but the per capita travel expenses shall not be less than 300 yuan (1) If a group of 20 people go on a tour, the school will give the total cost to the travel agency_____ Yuan (2) The school's travel agency charges a total of 12400 yuan to the travel agency after the end of the group tour, asking for the number of the school's tour to Nanxun; 2. In the plane rectangular coordinate system, take points a, B, C and D as vertices to form a parallelogram, where points a (2, N + 1), B (n-1, N + 4) and C (- 5-N, N + 5) are all on the same inverse scale function image, then n=____ The coordinates of vertex D are____ .
17. From the autumn of 2009 to May of this year, there was a serious drought in our city. From April 15 to 21 this year, both a and B middle schools had no water supply. The higher authorities immediately organized water supply activities, and each time they sent 7600 liters to a middle school and 4000 liters to B middle school. It is known that the per capita water supply is the same, the number of teachers and students in a middle school is two times that of B middle school, 20 less. (1) how many teachers and students are there in these two middle schools? (2) If you send bottled water, the price is 1 yuan / L; if you send drinking spring water by fire truck, you don't need to buy it, but you need to deliver water tower. The price of 500 liter water tower is 520 yuan / piece. Other expenses are ignored. Please calculate the cost of sending all bottled water or all drinking spring water by fire truck for the first time?
18. First dissolve: (A & sup2; - B & sup2; / A & sup2; - AB) / A & sup2; + 2Ab + B & sup2; / A, when B = - 1, then from - 2
19. A village wants to buy three kinds of trees. It is known that the price ratio of three kinds of trees is 2:2:3, and each tree is 200 yuan. Now it plans to use 210000 yuan to buy a total of 1000 trees If you buy tree a twice as much as tree B, and you just run out of money, how many trees can you buy If the purchase price of 10120 yuan is increased, how many trees can C buy at most on the premise that the total tree purchase remains unchanged?
20. 1. Given x + 1 / x = 4, then the value of X & sup2; + 1 / X & sup2; is () A. 12 b.1/2 c.16 D. uncertain 2. Given x = 2009, y = 2010, then (x + y) · X & sup2; + Y & sup2 / / X quartic - y quartic equals () 3. If x / 3 = Y / 4 = Z / 7, then the value of 3x + y + Z / y is ()