Given a = 2x ^ 2 + 3xy-2x-1, B = - x ^ 2 + XY-1. (1) find a + 2B; (2) if the value of 3A + 6B has nothing to do with X, find the value of Y

Given a = 2x ^ 2 + 3xy-2x-1, B = - x ^ 2 + XY-1. (1) find a + 2B; (2) if the value of 3A + 6B has nothing to do with X, find the value of Y

A+2B=5xy-2x-3;
y=0.4;

How to draw a straight line of length √ 2 with Geometer's Sketchpad
No way to draw directly?
If I want to draw a line with a length of 0.5, what should I do?

The hypotenuse of a 45 ° right triangle?
Using Pythagorean theorem
Root 3: root 2 and 1 are RT triangles with right angle sides
The length of hypotenuse is root 3
Root 5: that is the RT triangle with root 3 and root 2 as right angles
The hypotenuse is the root 5
0.7: can be enlarged to 7, and then use similar triangle to reduce the relationship of 1:10
At this point, the problem becomes to find the side length of 7, and the length becomes the RT triangle of 2 and 3
The length of the hypotenuse is 7, and it's 0.7 if you zoom in and out

Square ABCD, e and F are the midpoint of AD and ab respectively, connecting DF and CE to point P, connecting BP, and proving BP = BC

Given the quadratic function f (x) = AX2 + BX + C, f (2) = 0, f (- 5) = 0, f (0) = 1, find the quadratic function

∵ y = AX2 + BX + C satisfies f (2) = 0, f (- 5) = 0, f (0) = 1, that is, through three points a (2, 0), B (- 5, 0), C (0, 1), ∵ 4A + 2B + C = 025a − 5B + C = 0C = 1, the solution is a = − 110b = − 310c = 1, therefore, the analytic expression of the quadratic function is f (x) = − 110x2 − 310x + 1

There are three piles of chessmen, each pile has the same number of chessmen, and they are only black and white,
The number of sunspots in the first pile is the same as the number of white ones in the second pile. The number of sunspots in the third pile accounts for 1 / 5 of all the sunspots. If you put these three piles of pieces together, how many parts of the total number of white pieces?

The third pile of sunspots accounts for 1 / 5 of all sunspots, so the sunspots in the first pile and the second pile account for 4 / 5 of all sunspots. Because the number of sunspots in the first pile is the same as the number of white ones in the second pile, the number of sunspots in the first pile and the second pile is exactly equal to the number of chessmen in the first pile. If the number of chessmen in each pile is 4, the total number of chessmen in the third pile is 12, and the number of black ones is 5, then the number of white ones is 12-5 = 7, So white pieces account for 7 / 12 of all pieces

The image of function g (x) and the image of function y = (4-3x) / (x-1) are symmetric with respect to y = X-1

Let P (x0, Y0) be the image of the function y = (4-3x) / (x-1), and P '(x, y) be the symmetric point of P with respect to y = X-1, y = x0-1, x0 = y + 1x = Y0 + 1, Y0 = X-1 in y = (4-3x) / (x-1), Y0 = (4-3x0) / (x0-1) replace x0 = y + 1, Y0 = X-1

Pythagorean theorem. Teacher Wang took a matchbox and asked Songsong, "if you know the length and width of one side of the matchbox, can you calculate the length of the diagonal of the side?" Songsong answered, "you can calculate it with Pythagorean theorem." Teacher Wang put the matchbox on the table, and then asked Songsong, "can you prove Pythagorean theorem with matchbox?" after a while, Songsong happily told Mr. Wang, "Pythagorean theorem has been proved." do you know how Songsong proved it

Then in RT △ ACF, the square of AF is C square + C square, and because C square is a square + b square, when Fe intersects AB with m, then in △ AFM, am = B-A, FM = a + B, so a

ABCD plus ABC is equal to DCDC. What is ABCD

ABCD = 1000A+100B+10C+D
+ ABC = 100A+10B+C
-------------------------------------------------------------------
DCDC = 1000D+100C+10D+C
A=B=C=D=0

The upper base of a trapezoid is 8 cm. If the lower base is extended by 3 cm, it will become a parallelogram and the area will be increased by 24 square cm
Find the area of the original trapezoid. I really can't do it

Bottom = 8-3 = 5 cm;
Height = 24 × 2 △ 3 = 16 cm;
Original area = (8 + 5) × 16 △ 2 = 13 × 8 = 104 square centimeter;
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It is known that the side length of triangle ABC is a, B, C, the perimeter is 60cm, and a: B: C = 7:5:3, then the length of a, B, C is calculated
Please! Help me quickly, the day after tomorrow to hand in the answer,

Let a, B and C be 7x, 5x and 3x respectively,
7X+5X+3X=60
X=4
A. B and C are 28, 20 and 12