![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 1597 + 65 = 1535 + 65 + 62
= 1600 + 62 = 1662
b, 86 + 269 = 55 + 31 + 269
= 55 + 300 = 355
xin tiick
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(A=3^{1999}-7^{1957}\)
\(A=3^{1996}.3^3-7^{1956}.7\)
\(A=\left(3^4\right)^{499}.27-\left(7^4\right)^{489}.7\)
\(A=\left(\overline{...1}\right)^{499}.27-\left(\overline{...1}\right)^{489}.7\)
\(A=\left(\overline{...1}\right).\left(\overline{...7}\right)-\left(\overline{...1}\right).7\)
\(A=\overline{...7}-\overline{...7}\)
\(A=\overline{...0}\)
Vì \(\overline{...0}\text{⋮}5\)nên A⋮5 (đpcm)
Ta có:
\(B=51^n+47^{102}\)
\(B=\overline{...1}+47^{100}.47^2\)
\(B=\overline{...1}+\left(47^4\right)^{25}.\left(\overline{...9}\right)\)
\(B=\overline{...1}+\left(\overline{...1}\right)^{25}.\left(\overline{...9}\right)\)
\(B=\overline{...1}+\left(\overline{...1}\right)\left(\overline{...9}\right)\)
\(B=\overline{...1}+\overline{...9}\)
\(B=\overline{...0}\)
Vì \(\overline{...0}\text{⋮}10\)nên B⋮10 (đpcm)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Số số hạng tổng A có là : (999-201) +1= 799 (số hạng)
A=201+202 +203 +.......+ 997 + 998 +999
A=999+ 998 +997 +......+ 203 +202 +201
=>A=1200 +1200 +1200 +......+1200 +1200 +1200 ( 799 số hạng)
=>2A=1200 x 799 :2 = 958 800 : 2 = 479 400.
Vậy A = 479 400.
![](https://rs.olm.vn/images/avt/0.png?1311)
a)26+8x=6x+46
26-46=6x-8x
-20=-2x
=>x=10
b)3600:[(5x+335):x]=50
(5x+335):x=3600:50
(5x+335):x=72
=>5x+335=72x
=>335=67x
=>x=5
![](https://rs.olm.vn/images/avt/0.png?1311)
Nhầm, làm lại nhé!
\(\frac{x}{13}+\frac{15}{26}=\frac{46}{52}\)
\(\frac{x}{13}+\frac{15}{26}=\frac{23}{26}\)
\(\frac{x}{13}=\frac{23}{26}-\frac{15}{26}\)
\(\frac{x}{13}=\frac{23}{26}-\frac{15}{26}\)
\(\frac{x}{13}=\frac{4}{13}\)
\(\Rightarrow x=\frac{13.4}{13}=4\)
Vậy \(x=4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
15/26 + x/16 = 46/52
x/16 = 46/52 - 15/26
x/16 = 1/4
x/16 = 4/16
Suy ra: x = 4
Vậy x = 4
\(\frac{15}{26}+\frac{x}{16}=\frac{46}{52}\)
\(\Rightarrow\frac{x}{16}=\frac{45}{52}-\frac{15}{26}\)
\(\Rightarrow\frac{x}{16}=\frac{4}{13}\Rightarrow\frac{64}{208}=\frac{x}{16}=\frac{64}{208}=\frac{x}{208}\Rightarrow x=64\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
720 : (x - 17) = 12
x – 17 = 60
x = 60 + 17
x = 77
b)
(x - 28) : 12 = 8
x – 28 = 8 . 12
x – 28 = 96
x = 124
c)
26 + 8x = 6x + 46
8x – 6x = 46 – 26
2x == 20
x = 10
d)
3600 : [(5x + 335) : x] = 50
(5x + 335) : x = 72
5x + 335 = 72x
67x = 335
x = 5
\(15-5x=\left(26-1597\right)-\left(46-1597\right)\)
\(15-5x=26-1597-46-1597\)
\(15-5x=\left(26-46\right)-\left(1597-1597\right)\)
\(15-5x=0-20\)
\(15-5x=-20\)
\(5x=15-\left(-20\right)\)
\(5x=35\)
\(x=35\div5\)
\(x=7\)
Cậu ơi! Vế bên phải tớ làm bằng quy tắc dấu ngoặc nha
15 - 5x = ( 26 - 1597) - ( 46 - 1597)
<=> 15 - 5x = -1571 - (- 1551 )
<=> 15 - 5x = 0
<=> -5x =15
<=> x =15 : -5
<=> x = 3
Vậy x = 3