The multiplication of the following two polynomials, which cannot be expressed by the square difference formula, is () A. （-2a+3b）（2a+3b）B. （-2a+3b）（-2a-3b）C. （2a+3b）（-2a-3b）D. （-2a-3b）（2a-3b）

The multiplication of the following two polynomials, which cannot be expressed by the square difference formula, is () A. （-2a+3b）（2a+3b）B. （-2a+3b）（-2a-3b）C. （2a+3b）（-2a-3b）D. （-2a-3b）（2a-3b）

A. (- 2A + 3b) (2a + 3b) can use the square difference formula, so this option is wrong; B, (- 2A + 3b) (- 2a-3b) can use the square difference formula, so this option is wrong; C, (2a + 3b) (- 2a-3b) can't use the square difference formula, so this option is correct; D, (- 2a-3b) (2a-3b) can use the square difference formula, so this option is wrong

1. Calculate the following formula (3a-3b) (3a + 2a) with the square difference formula
Please explain the calculation process

This should be used in the cross multiplication formula: (x times y) times (x times z) = x ^ 2 + (YZ) x + YZ
（3a-3b)（3a+2a）
=9a^2+(-3b+2a)3a+(-3b)2a
=9a^2-9ab+6a^2-6ab
=9a^2+6a-15ab

The number of zeros of function f (x) = loga (x + 1) + x2-2 (0 < a < 1) is ()
A. 3B. 2C. 1D. 0

∵ f (x) = loga (x + 1) + x2-2 = 0 (0 < a < 1) ∵ loga (x + 1) = 2-x2 (0 < a < 1), which can be transformed into the number of intersections of function y = loga (x + 1) and y = 2-x2. By analysis, it can be concluded that there are two intersections, that is, the number of zeros of function f (x) = loga (x + 1) + x2-2 (0 < a < 1) is 2

It is known that the parabola y = - x2 + 2x + M-1 has two intersections A and B with the x-axis. (1) find the value range of M; (2) if the coordinate of point a is (- 1,0), find the analytical formula of the parabola and the coordinate of the top point C; (3) is there a point P (not coincident with point C) on the parabola in question (2) so that s △ PAB = s △ cab? If it exists, find out the coordinates of point p; if not, explain the reason

(1) There are two intersections between the ∵ parabola and the x-axis, that is, b2-4ac = 22-4 × (- 1) × (m-1) = 4 + 4m-4 = 4m & gt; 0, the solution is M & gt; 0; (2) the coordinates of ∵ a are (- 1,0), ∵ - (- 1) 2 + 2 × (- 1) + M-1 = 0, the solution is m = 4, and the analytical formula of ∵ parabola is y = - x2 + 2x + 4-1 = - x2 +

If the parabola y = AX2 and y = 3x2 have the same shape and opening direction, then the value of a is?

a=3

21 36 33 16 73 29 35 39 49 24 67 19 18 57 Prime: Total:

Prime: 73 29 67 19 total: 21 36 33 16 35 39 49 24 18 57

Decomposition factor: (X-Y) & #179; - 4 (X-Y) & #178; + 4 (X-Y)
It's a & # 178; - 2Ab + B & # 178;, but I don't know how to split it. Please explain

It is found that there is no difference between the two factors
（x-y）【（x-y）²-4（x-y）+4】
=（x-y）（x-y-2）²

It is known that x 2 + 5Y 2-4xy-6y + 9 = 0

X 2 + 5Y 2-4xy-6y + 9 = 0, x 2 + 4Y 2-4xy + y 2-6y + 9 = 0, (x-2y) 2 + (Y-3) 2 = 0, x-2y = 0, Y-3 = 0, the solution is y = 3, x = 6

5x-4.7x = 9 / 10 solution equation

5x-4.7x = 9 / 10
0.3x=0.9
x=3

The equation of one variable and one degree
The distance between Xi'an station and Wuhan station is 1500km. A slow train departs from Xi'an at a speed of 65km / h, and an express train departs from Wuhan at a speed of 85km / h. If the two trains are facing each other, the slow train will drive for 30 minutes first, and the express train will run for a few hours before they meet?
Add money before 14 o'clock

Set the express train to meet after X hours
Because the local train started 30 minutes, that is, 0.5 hours
Therefore, we walked 0.5x65km/h = 32.5Km first
1500-32.5 = 1467.5km left
(65+85)x=1467.5
The solution is x = 9 and 47 / 60, which is about 9.783
So: after 9 and 47 / 60 hours, the two trains meet, that is (9.783 hours later)