/-7 / + / + 3.5 / =? 7 - / - 5 / =? 3 / 19 times / - 38 / / 0.1 / divided by / 2 / 5 / OK, I'll add another 5 points,

/-7 / + / + 3.5 / =? 7 - / - 5 / =? 3 / 19 times / - 38 / / 0.1 / divided by / 2 / 5 / OK, I'll add another 5 points,

10.5 2 -6 0.25

If (x + m) (x + 2) = the square of X - 6x + N, then M = n=
If (2x-3) (5-2x) = the square of AX + BX + C, then a + B + C=
3 (2x-3y)(2x-3y)-（y+3x)(3x-y)
4 (3x+2y)(2x+3y)-(x-3y)(3x+4y)

First question, M = - 8, n = - 16
Second, - 15
Question 3, - 5x * x-12x * y + 10Y * y
Question 4, 3x * x + 17x * y + 12Y * y

If △ ABC is known, extend BC to d so that CD = BC. Take the midpoint F of AB and connect FD to AC at point E. (1) find the value of aeac; (2) if AB = a, FB = EC, find the length of AC

(1) F is the midpoint of AB, M is the midpoint of BC, FM = 12ac. ∵ FM ∥ AC, ∵ CED = ∠ MFD, ∵ ECD = ∠ FMD. ∵ FMD ∵ ECD. ∵ DCDM = ECFM = 23. ∵ EC = 23fm = 23 × 12ac = 13ac. ∵ aeac = AC − ECAC = AC − 13acac = 23. (2) ∵ AB = a, ∵ FB = EC, ∵ EC = 12a. ∵ EC = 13ac, ∵ AC = 3ec = 32A

Given that point a (4,0) and point B (2,2), M is a moving point on the ellipse X / 25 + Y / 9 = 1, then the maximum value of | Ma | + | MB | is
Math master, please write down the most simple process

Geometric method, the answer is 10 + 2 √ 10, first draw the left focus C (- 4,0), do AC extension line intersection left half ellipse as P, remove any point on the ellipse as P. according to the figure, obviously AC + PC + Pb = 2A + AC = AC + cm + BM ≥ am + BM, that is, point P is the point m | Ma | + | MB | the maximum value is 2A + AC = 10 + 2 √ 10

As shown in the figure, the side length of square paper ABCD is 3, points E and F are on sides BC and CD respectively, and AB and AD are folded with AE and AF respectively. Points B and D are exactly at point g. given be = 1, then the length of EF is ()
A. 32B. 52C. 94D. 3

According to the properties of folding, we get: eg = be = 1, GF = DF, let DF = x, then EF = eg + GF = 1 + X, FC = dc-df = 3-x, EC = bc-be = 3-1 = 2, in RT △ EFC, ef2 = EC2 + FC2, that is, (x + 1) 2 = 22 + (3-x) 2, the solution is: x = 32, DF = 32, EF = 1 + 32 = 52

If the two roots of the equation 2x & # 178; - 2x-1 = 0 are x1, X2, solve the equation and find the values of the following expressions
①x1²+x2² ②x1²-x2² ③x2/x1+x1/x2 ④2x2²-x1x2+2x1-3

I'm sorry. I won't put a tick under the root
x1+x2=﹣b／a=1 x1x2=c／a=﹣1/2
①:x1²+x2²=(x1+x2)²-2x1x2=1+1=2
②:x1-x2=√（x1-x2)²=√[﹙x1+x2﹚²-4x1x2)]=√3
x1²-x2²=(x1+x2)(x1-x2)=√3
③x2/x1+x1/x2=x2²+x1²／x1x2=-4
④ ∵ X2 is the root of the equation. Take x2 into ∵ 2x2 & # 178; - 2x2-1 = 0, that is, 2x2 & # 178; = 1 + 2x2
2x2²-x1x2+2x1-3=1+2x2-x1x2+2x1-3=2(x1+x2)-x1x2-2=1／2

As shown in the figure, e and F are two points on diagonal AC of quadrilateral ABCD, AF = CE, DF = be, DF / / be
Is triangle AFD congruent with triangle CEB? Please explain the reason
Judge the shape of quadrilateral ABCD and explain the reason

It is proved that: (1) DF be,
∴∠DFE=∠BEF．
AF = CE, DF = be,
∴△AFD≌△CEB（SAS）．
(2) From (1), we know △ AFD ≌ △ CEB,
∴∠DAC=∠BCA,AD=BC,
∴AD∥BC．
A quadrilateral ABCD is a parallelogram

Find the vertical formula of four digit divided by three digit and two digit
Such as 8760 / 7301508 / 29
And 27144 / 312

The cosine value of dihedral angle a1-bd-c1 in cube abcd-a1b1c1d1 is______ ．

As shown in the figure, take the midpoint o of BD, connect a1o and C1O, then a1o ⊥ BD, C1O ⊥ BD, х a1oc1 is the plane angle of the dihedral angle a1-bd-c1. If the edge length of the cube is 1, then a1c1 = 2, a1o = C1O = 62, х cos ∠ a1oc1 = 64 + 64 − 22.62.62 = − 13, so the answer is: − 13

Finding the value of A4 + 1 / A4 for the quadratic equation a2-3a + 1 = 0

A2-3a + 1 = 0 can be changed into a + 1 / A-3 = 0, that is, a = 3. Therefore, A2 + 1 / A2 = 7 can be obtained from the square of (a + 1 / a) equal to 9. Similarly, A4 + 1 / A4 = 47 can be obtained