Mingming is 12 years old and Qiangqiang is 7 years old. When the sum of their ages is 45, how old are they?

Mingming is 12 years old and Qiangqiang is 7 years old. When the sum of their ages is 45, how old are they?

45 - (12-7) = 40 (years old) 40 △ 2 = 20 (years old) 45-20 = 25 (years old) a: it's obviously 25 years old

Luo Zhen is 12 years old and Xiao Ming is 7 years old. When the sum of their ages is 45 years old, Xiao Ming is () years old and Luo Zhen is () years old

(45-12-7)÷2=13
Xiao Ming = 13 + 7 = 20 years old
Luo Zhen = 13 + 12 = 25 years old
Luo Zhen is 12 years old and Xiao Ming is 7 years old. When the sum of their ages is 45 years old, Xiao Ming is 20 years old and Luo Zhen is 25 years old

Square of 1 - (a - (1-A) part ÷ (square of a-2a + 1) part (square of A-A + 1)

1-[a-1/(1-a)]²÷ (a²-a+1)/(a²-2a+1)
=1-[(a²-a+1)/(a-1)]²÷[(a²-a+1)/(a-1)²]
=1-(a²-a+1)²/(a-1)²×(a-1)²/(a²-a+1)
=1-(a²-a+1)
=-a²+a

Simple calculation of 38 * (1 / 85 + 1 / 47) - 47 * (1 / 38-1 / 85) + 85 * (1 / 38-1 / 47)

38*（1/85+1/47）-47*（1/38-1/85）+85*（1/38-1/47）
=38/85+38/47-47/38+47/85+85/38-85/47
=(38+47)/85+(38-85)/47+(85-47)/38
=1-1+1
=1

When Lim x approaches zero, what about (1 + x) 2 / x

You mean LIM (x → 0) (1 + x) ^ (2 / x)?
If so, then
lim(x→0）(1+x)^(2/x)
=lim(x→0）[(1+x)^(1/x)]^2
=e^2

The solution of 2x + 5Y = 3 + n 3x + y = 18 + n is suitable for the equation x + y = 0 to find the value of n

2x+5y=3+n
3x+y=18+n
The solution of the equations is as follows
x=(87+4n)/13
y=(n-27)/13
According to the meaning of the question: (87 + 4N) / 13 + (n-27) / 13 = 0
The solution is: n = - 12

A simple method is used to calculate: 4 + 14 + 24 + 34 + 44 + 54 + 64 + 74 + 84 + 94 + 104 + 114 + 124 + 134 =?

Arithmetic sequence, each term is 10 times different
S=（4+134）*14/2=138*7=966
It's the same reason that 1 is added to 100 and the result is 5050

9 ^ n + 1 -- 3 ^ n = 27, find n
It's 72, not 27

9^N+1=3^2N+2
So 9 ^ n + 1-3 ^ n = 3 ^ n + 2
3^N+2=27
Because 3 ^ 3 = 27
So n + 2 = 3
So n = 1
Ask again if you don't understand
If it's equal to 72
That's 3 ^ n + 2 = 72
I am a junior high school student
Use a calculator

Is a polynomial minus 3x square - 5x + 1, the minus sign will be copied into plus, the result is 5x square + 3x-7
Come on, you must answer the question immediately after 10 minutes, plus a reward of 100

Rule: if subtraction is regarded as addition, the result is exactly twice as much as the actual subtraction
Solution: the correct result is: 5x & # 178; + 3x-7-2 (3x & # 178; - 5x + 1) = - X & # 178; + 13x-9

How to do 2000 minus 197 with simple algorithm

=2000-（200-3）
=2000-200+3
=1800+3
=1803