2^ n +1=128
2n-15=17
2.3^n=162
(7^n-11)^3=2^5.5^2+200
Tim x biet
a 2.3^x=162
b 2^x-15=17
c (7.x-11)=2^5.5^2+200
2.3x=162
3x=162:2
3x=81
3x=34
=>x=4
2x-15=17
2x=17+15
2x=32
2x=25
=>x=5
(7x-11)3=25.52+200
(7x-11)3=1000
(7x-11)3=103
7x-11=10
7x=10+11
7x=21
x=21:7
x=3
Tìm x thuộc số tự nhiên biết
a 2.3^x=162
b 5^x=125
c 2^x-15=17
d (7^x-11)^3=2^5.5^2+200
e 3^2^x=81
f 5^2^x-^3-2.5^2=5^2.3
tim \(x\in\)N biet
a . \(x^{10}=x\)
b . \(\left(2x-15\right)^5=\left(2x-15\right)^3\)
c . \(\left(7\times n-11\right)=2^5.5^2+200\)
a) \(x^{10}=x\)
\(\Rightarrow x^{10}-x=0\)
\(\Rightarrow x\left(x^9-1\right)=0\)
=> x=0 HOẶC \(x^9-1=0\)
=>x=0 HOẶC x=1
tìm x thuộc n:
\(\left(7x-11\right)^3=2^5.5^2+200\)
giúp mik nha mik cần gấp
(7x−11)3 = 25 . 52 + 200
(7x−11)3 = 32 . 25 + 200
(7x−11)3 = 1000
(7x−11)3 = 103
7x−11 = 10
7x = 10 + 11
7x = 21
x = 21 : 7
x = 3
(7x−11)3 = 25 . 52 + 200
(7x−11)3 = 32 . 25 + 200
(7x−11)3 = 1000
(7x−11)3 = 103
7x−11 = 10
7x = 10 + 11
7x = 21
x = 21 : 7
x = 3
Tìm n thuộc N biết:
\(\left(7n-11\right)^3=2^5.5^2+200\)
\(\Rightarrow\left(7n-11\right)^3=32\times25+200\)
\(\Rightarrow\left(7n-11\right)^3=1000\)
\(\Rightarrow7n-11=10\)
\(\Rightarrow7n=10+11\)
\(\Rightarrow n=21:7=3\)
\(\left(7n-11\right)^3=2^5.5^2+200\)
\(\left(7n-11\right)^3=32.25+200\)
\(\left(7n-11\right)^3=800+200\)
\(\left(7n-11\right)^3=1000\)
=>TH1:(7n-11)3=103
=>7n-11=10
=>7n=10+11=21
=>n=21:7=3
TH2: (7n-11)3=-103
=>7n-11=-10
=>7n=-10+11
=>7n=1
=>n=1:7=1/7
Mà n thuộc N nên n=3
Kết luận n=3
Trà My~ Cần j lm 2 TH; you lm sai roay đs. Vì nếu (7n-11)3=-10 thì lm sao -103=1000 cho được
22) tim x thuoc n biết
a)2^x=16
b)4^x=64
c)15^x=225
d)2^x-15=17
e)2^x-64=2^6
f)(7x-11)^3=2^5.5^2+200
a) \(2^x=16\)
\(2^x=2^4\)
\(\Rightarrow x=4\)
vay \(x=4\)
b) \(4^x=64\)
\(4^x=4^3\)
\(\Rightarrow x=3\)
vay \(x=3\)
c) \(15^x=225\)
\(15^x=15^2\)
\(\Rightarrow x=2\)
vay \(x=2\)
d) \(2^x-15=17\)
\(2^x=32\)
\(2^x=2^5\)
\(\Rightarrow x=5\)
vay \(x=5\)
e) \(2^x-64=2^6\)
\(2^x=2^6+64\)
\(2^x=128\)
\(2^x=2^7\)
\(\Rightarrow x=7\)
vay \(x=7\)
f) \(\left(7x-11\right)^3=2^5.5^2+200\)
\(\left(7x-11\right)^3=800+200\)
\(\left(7x-11\right)^3=1000\)
\(\left(7x-11\right)^3=10^3\)
\(\Rightarrow7x-11=10\)
\(\Rightarrow7x=21\)
\(\Rightarrow x=3\)
vay \(x=3\)
(7.X-11)^3=2^5.5^2+200
Thế này mới đúng
\(\left(7x-11\right)^3=2^5.5^26+200\)
= \(\left(7x-11\right)^3=1000\)
= \(\left(7x-11\right)^3=10^3\)
= \(\left(7x-11\right)=10\)
= \(7x=10+11\)
= \(7x=21\)
=> \(x=21:7\)
=> x = 3
Bạn thử vào x chắc chắn đúng 99,9%
= \(\left(7.x-11\right)^3=1000\)
= \(\left(7.x\right)^3=1000+11=1011\)
= \(\left(7.x\right)^3=1011\)
= \(1011:7=\frac{1011}{7}\)
= \(x^3=\frac{1011}{7}=1,433790434\)
(7.x-11)mũ 3 = 2 mũ 5.5 mũ 2=200
\(\Leftrightarrow7x-11=20\)
hay x=31/7
Tìm x biet x thuộc so tự nhien :
a) 2x-15=17
b) (7.x-11)=2^5.5^2+200
c) (2x-15)5=(2x-15)3