The simple calculation is the simple calculation, that is, the simple calculation is the simple calculation. 2.4 + 12.4 + 12.7 + 12.7 + 12.7 + 12.7 + 12.7 + 7.7 + 47.7 + 47.6 + 47.6 + 37.6 + 37.3.3 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp & nbsp & nbsp; & nbsp; & nbsp & nbsp; & nbsp; & nbsp & nbsp & nbsp & nbsp; & nbsp & nbsp; & nbsp & nbsp; & nbsp & nbsp & nbsp & nbsp & nbsp; & nbsp & nbsp; & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & nbsp; & nbsp& nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 4200÷25÷4 17×（106-312÷13）136÷17-0.32×10．

（1）2.4+12.7+47.6+37.3=2.4+47.6+（37.3+12.7）=50+50=100；（2）15×21+15×78+15=15×（21+78+1）=15×100=1500；（3）63×99=63×100-63×1=6300-63=6237；（4）29×47-47×19=（29-19）×47=10×47=470；（5）32×125×25=8×125×（4×25）=1000×100=100000；（6）4200÷25÷4=4200÷（25×4）=4200÷100=42；（7）17×（106-312÷13 ）=17×（106-24）=17×82=1394；（8）136÷17-0.32×10=8-3.2=4.8．

Using factorization method to solve the equation ① 4x (2-x) = 3 (2-x) ② 3 (x-1) x = 2-2x ③ 4 (x + 1) ^ 2 = 9 (2x-1) ^ 2 ④ (x-1) ^ 2 = 1-x ^ 2

①4x(2-x)=3(2-x)
(4x-3)(2-x)=0
x1=3/4 x2=2
②3（x-1）x=2-2x
3(x-1)x=2(1-x)
(x-1)(3x+2)=0
x1=1 x2=-2/3
③4(x+1)^2=9(2x-1)^2
[2(x+1)-3(2x-1)][2(x+1)+3(2x-1)]=0
(-4x+5)(8x-1)=0
x1=5/4 x2=1/8
④（x-1）^2=1-x^2
(x-1)^2=(1+x)(1-x)
(x-1)^2+(1+x)(x-1)=0
(x-1)(x-1+1+x)=0
2x(x-1)=0
x1=0 x2=1

(- 81) △ 2 and 1 / 4 × 4 / 9 △ (- 16)
How to get 81 × 4 / 9 × 4 / 9 × 16 = 1
It's mainly about how to get four out of nine from two and one out of four

(- 81) △ 2 and 1 / 4 × 4 / 9 △ (- 16)
=81÷9/4×4/9×1/16
=81×4/9×4/9×1/16
=1

In the process of solving the equation, the basis of merging similar terms is_ The coefficient is changed to 1_ .

In the process of solving the equation, the basis of merging similar terms is_____ Multiplicative distributive law____ The coefficient is changed to 1____ If both sides divide by a number not equal to 0, the equation still holds_____ .

Calculation: 1-2, 1-4, 1-8, 1-16, 1-32, 1-64, 1-128, 1 =?

Is it 1-1 / 2-1 / 4-1 / 8-1 / 16-1 / 32-1 / 64-1 / 128 =?
The sum formula of equal ratio sequence: SN = A1 (1-Q ^ n) / (1-Q) = (A1 an × q) / (1-Q) (Q ≠ 1)
The above formula = 1 - (1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 + 1 / 32 + 1 / 64 + 1 / 128)
=1-(1/2*(1-1/2^7)/(1-1/2))=1/128

As shown in the figure, AB is the diameter of ⊙ o, the extension lines of chord BD and Ca intersect at point E, and the extension line of EF perpendicular to Ba intersects at point F. verification: (1) be · de + AC · CE = CE2; (2) EDF = ∠ CDB; (3) e, F, C, B are co circular

(1) Connect CD, as shown in the figure below: from the circular angle theorem, we can get ∠ C = ∠ B, and then ∠ BEC is the common angle of △ Abe and △ CDE,  △ Abe ∽ CDE, ｜ be: CE = AE: De, ｜ be · de = CE · AE ｜ be · de + AC · CE = CE2 (3 points) (2) ∵ △ Abe ∽ CDE, ∽ EDC = ∠ FDB, ∽ EDF = ∠ CDB, (6 points) (3) ∵ AB is the diameter of ⊙ o, and ∽ ECB = 90 ° is EB In the same way, FH = 12be, so the distances from e, F, C and B to h are equal, and the four points e, F, C and B are in a circle. (10 points)

27.2 divided by 3.58 = what

3.597765363

In △ ABC, D is a point on AB, AE ⊥ CD is e, ad = 2, DB = 1, AC = root 6, ∠ ACB = 60 °, 1) triangle ACD is similar to ABC; (2) calculate AE

1) ∵ AC / AB = √ 6 / 3, AD / AC = 2 / √ 6 = √ 6 / 3 ∵ AC / AB = ad / AC3 and ∠ DAC = ∠ cab ∵ triangle ACD is similar to ABC. (SAS) 2) ∵ AC / SINB = AB / sin60 ∵ SINB = √ 2 / 2 ∵ B = 45 ∵ triangle ACD is similar to ABC. (SAS) ∵ ace = ∠ B = 45 ∵ AE & 178; + e

A. The sum of two numbers B is 23, the quotient of a divided by B is 2 and the remainder is 5. What are the numbers a and B?

A+B=23
A=2×B+5
∴ B=6 A=17

What about the Vandermonde determinant without a line?

There's something wrong with the determinant you gave. It's N + 1 row, NL column
For this kind of Vandermonde determinant, if it lacks one row, you can add this row. At the same time, in order to form the determinant, you need to add another column. In order to distinguish from the original elements, the new column can be added to the 0 to n power of A. in this way, a standard Vandermonde determinant is formed. For the new determinant, the remainder of the elements in the I + 1 row and the N + 1 column is what we require, You can expand the new determinant by column n + 1, one of which is a ^ IAI + 1, N + 1. For the coefficient of I power of a in the calculation result of Vandermonde formula, it is the algebraic cofactor of the elements in row I + 1, column n + 1, and then you should know