Binary linear fractional equations 1/x + 1/y =1 5/x +（1/y + 1/x）* 9 =1

Binary linear fractional equations 1/x + 1/y =1 5/x +（1/y + 1/x）* 9 =1

Let 1 / x = x, 1 / y = y
X+Y=1...（1）
5X+（Y+X）*9=1...（2）
Generation Y = 1-x from (1) (2)
5X+（1-X+X）*9=1
5X+9=1
X=-8/5
Y=1-（-8/5）=13/5
x=1/X=-5/8
y=1/Y=5/13

On the expansion of power series of functions
Expand the function to a specified power series, and write its convergence interval
The function f (x) = lgx is expanded into a power series of (x-1)
Lgx = (1 / ln10) (superscript "infinite", subscript "n = 1") ∑ (- 1) ^ (n-1) * [(x-1) ^ n] / N convergence interval: (0,2]

We know that if we expand the logarithmic function ln (1 + x) into a power series with respect to x, there is a
ln(1+x)=x-x^2/2+x^3/3-x^4/4+… +(-1)^(n-1)* x^n/n+… -1＜x≤1
Using the formula of changing bottom, f (x) = lgx = LNX / ln10 = ln [1 + (x-1)] / ln10
So f (x) = (1 / ln10) ∑ (- 1) ^ (n-1) * [(x-1) ^ n] / N (- 1)

What is 0.65?

0.65 * 60 = 39 (points)

If non-zero real numbers a, B (a ≠ b) satisfy a2-a + 2007 = 0, b2-b + 2007 = 0, then: 1A + 1b=______ ．

∵ if non-zero real numbers a, B (a ≠ b) satisfy a2-a + 2007 = 0, ①, b2-b + 2007 = 0, ②, ① - ②, then (a-b) (a + B-1) = 0, ∵ a ≠ B, ∵ a + B = 1, ① + ② (a + B) 2-2ab - (a + b) + 4014 = 0, ∵ a + B = 1, ab = 2007, ∵ 1A + 1b = a + bab = 12007

Take off formula calculation (simple calculation is needed) 216 + 384 + 404 + 796 154 - (54 + 98) 17 × 25 × 4 160-60 △ 2 420 △ 35 237-58 + 163-242

（1）216+384+404+796，=（216+384）+（404+796），=600+1200，=1800；（2）154-（54+98），=154-54-98，=100-98，=2；（3）17×25×4，=17×（25×4），=17×100，=1700；（4）160-60÷2，=160-30，=130；（5）420÷35，=（420÷7）÷（35÷7），=60÷5，=12；（6）237-58+163-242，=（237+163）-（58+242），=400-300 ，=100．

Merge similar items, remove brackets - 7a + 3A=

-7a+3a=-4a;
I'm very glad to answer your questions. Skyhunter 002 will answer your questions
If you don't understand this question, you can ask,

For a bottle of alcohol, pour out 13 grams for the first time and then pour back 40 grams; pour out 59 grams of alcohol left in the bottle for the second time; pour out 180 grams for the third time and there are 60 grams left in the bottle. How many grams of alcohol are there in the original bottle?

(180 + 60) / (1-59), = 240 △ 49, = 540 (g); (540-40) / (1-13), = 500 △ 23, = 750 (kg). A: there was 750 g of alcohol in the original bottle

Three and one eighth, three and eight nineties, three and nine tenths

25 out of 8, 35 out of 9, 39 out of 10

What is the quotient of the product of 7 / 12 and its reciprocal minus 0.125 divided by 3 / 18

Love Zhang Han 521
(7/12×12/7-0.125)÷3/18＝(1-0.125)×18/3＝0.875×18÷3＝5.25
Is that so? Good luck and goodbye

How to find the analytic formula of quadratic function y = a (X-H) + k
y=（60+6x）（120-6x）

y=（60+6x）（120-6x）
=7200-360x+720x-36x²
=-36x²+360x+7200
=-36(x²-10x)+7200
=-36(x²-10x+25)+7200+900
=-36(x-5)²+8100
a=-36,h=5,k=8100
It is suggested that the formula method should be used to solve the problem