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
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
NN
25 tháng 8 2017
\(a,\left(7x-11\right)^3=2^5.5^2+200.\)
\(\left(7x+11\right)^3=32.25+200.\)
\(\left(7x+11\right)^3=800+200.\)
\(\left(7x-11\right)^3=1000.\)
\(\left(7x-11\right)^3=10^3.\)
\(\Rightarrow7x-11=10.\)
\(\Rightarrow x=\left(10+11\right):3=7\in Z.\)
Vậy.....
\(b,3^x+25=26.2^2+2.3^0.\)
\(3^x+25=26.4+2.\)
\(3^x+25=104+2.\)
\(3^x+25=106.\)
\(3^x=106-25.\)
\(3^x=81.\)
\(3^x=3^4\Rightarrow x=4\in Z.\)
Vậy.....
\(c,2^x+3.2=64.\)(có vấn đề).
\(d,5^{x+1}+5^x=750.\)
\(5^x.5^1+5^x+1=750.\)
\(5^x\left(5^1+1\right)=750.\)
\(5^x\left(5+1\right)=750.\)
\(5^x.6=750.\)
\(5^x=750:6.\)
\(5^x=125.\)
\(5^x=5^3\Rightarrow x=3\in Z.\)
Vậy.....
\(e,x^{15}=x.\)
\(\Rightarrow x\left(x^{14}-1\right)=0\Rightarrow\left\{{}\begin{matrix}x=0\\x=1\end{matrix}\right..\)
\(f,\left(x-5\right)^4=\left(x-5\right)^6.\)
\(\Leftrightarrow\left(x-5\right)^4-\left(x-5^6\right)=0.\)
\(\Leftrightarrow\left(x-5\right)^4\left[1-\left(x-5\right)^2\right]=0.\)
\(\Leftrightarrow\left(x-5\right)^4\left(1-x+5\right)\left(1+x-5\right)=0.\)
\(\Leftrightarrow\left(x-5\right)^4\left(6-x\right)\left(x-4\right)=0.\)
\(\Leftrightarrow\left(x-5\right)^4=0\Rightarrow x-5=0\Rightarrow x=5\in Z.\)
\(6-x=0\Rightarrow x=6\in Z.\)
\(x-4=0\Rightarrow x=4\in Z.\)
Vậy.....
KN
2 tháng 7 2015
b) x^10=1x
=> x=0 ; 1
c)(2x-15)^5=(2x-15)^3
=> (2x-15)^4 = (2x-15)^2
=> (2x-15)^2 =1
=> 2x-15=1
=> x=8
NT
2
KN
27 tháng 8 2015
720 : [41-(2x-5)] =2^3 . 5
<=> 41-(2x-5)=720:40=18
<=> 2x-5=41-18=23
<=>2x=23+5=28
<=> x=28:2=14
2^x-15=17
<=> 2^x=17+15=32
<=> 2^x=2^5
<=> x=5
(7x-11)^3= 2^5.5^2+200
<=> (7x-11)^3=1000
<=> (7x-11)^3=10^3
<=> 7x-11=10
<=> 7x=10+11=21
<=> x=21:7=3
20 tháng 9 2017
a) 2x - 15 = 17
2x = 25
b) ( 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
like nha
LA
8
20 tháng 9 2017
a) \(2^x\)\(-\)\(64\)\(=\)\(2^6\)
\(2^x\)\(-\)\(2^6\)\(=\)\(2^6\)
\(2^x\) \(=\)\(2^6\)\(+\)\(2^6\)
\(2^x\) \(=\) \(64\)\(+\)\(64\)
\(2^x\) \(=\) \(128\)
\(\Rightarrow\) \(2^x\) \(=\) \(2^7\)
b) \(\left(7x-11\right)\)\(^3\)\(=\)\(2^5\)\(.\)\(5^2\)\(+\)\(200\)
\(\left(7x-11\right)\)\(^3\)\(=\)\(32\)\(.\)\(25\)\(+\)\(200\)
\(\left(7x-11\right)\)\(^3\)\(=\) \(1000\)
\(\left(7x-11\right)\)\(^3\)\(=\) \(10^3\)
\(\Rightarrow\)\(7x-11\)\(=\)\(10\)
\(7x\) \(=\)\(10+11\)
\(7x\) \(=\) \(21\)
\(x\) \(=\) \(21\)\(:\)\(7\)
\(x\) \(=\) \(3\)
DD
20 tháng 9 2017
\(2^x-64=2^6\)
\(2^x-64=64\)
\(2^x=64+64\)
\(2^x=128\)
\(\)Vì \(128=2^7\) \(\Rightarrow x=7\)
LN
1
15 tháng 6 2016
x^20-x=0
x(x^19-1)=0
x= 0
hoặc x ^ 19 =1
x = 0 hoặc x= 1
16 tháng 6 2016
(7x-11)3=25.22+200
(7x-11)3=25+2+200
(7x-11)3=27+200
(7x-11)3=128+200
(7x-11)3=328
xong hết bt
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 \(x=3\)
a, x=4
b, x=3
c, x=2
d, =2