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a) \(x-2=-6\)
\(x=-6+2\)
\(x=-4\)
b) \(15-\left(x-7\right)=-21\)
\(x-7=36\)
\(x=43\)
c) \(4.\left(3x-4\right)-2=18\)
\(4\left(3x-4\right)=20\)
\(3x-4=5\)
\(3x=9\)
\(x=3\)
d) \(\left(3x-6\right)+3=32\)
\(3x-6=29\)
\(3x=29+6\)
\(3x=35\)
\(x=\frac{35}{3}\)
e) \(\left(3x-6\right).3=32\)
\(3x-6=\frac{32}{3}\)
\(3x=\frac{32}{3}+6\)
\(3x=\frac{50}{3}\)
\(x=\frac{50}{9}\)
f) \(\left(3x-6\right):3=32\)
\(3x-6=96\)
\(3x=102\)
\(x=34\)
g) \(\left(3x-6\right)-3=32\)
\(3x-6=35\)
\(3x=41\)
\(x=\frac{41}{3}\)
h) \(\left(3x-2^4\right).7^3=2.7^4\)
\(\left(3x-2^4\right)=2.7=14\)
\(\left(3x-16\right)=14\)
\(3x=14+16=30\)
\(x=10\)
i) \(\left|x\right|=\left|-7\right|\)
\(\left|x\right|=7\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)
k) \(\left|x+1\right|=2\)
\(\Rightarrow\orbr{\begin{cases}x+1=2\\x+1=-2\end{cases}\Rightarrow\orbr{\begin{cases}x=1\\x=-3\end{cases}}}\)
l) \(\left|x-2\right|=3\)
\(\Rightarrow\orbr{\begin{cases}x-2=3\\x-2=-3\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=-1\end{cases}}}\)
m) \(x+\left|-2\right|=0\)
\(x+2=0\)
\(x=-2\)
o) \(72-3\left|x+1\right|=9\)
\(3\left|x-1\right|=63\)
\(\left|x-1\right|=21\)
\(\Rightarrow\orbr{\begin{cases}x-1=21\\x-1=-21\end{cases}\Rightarrow\orbr{\begin{cases}x=22\\x=-20\end{cases}}}\)
p) Ta có: \(\left|x-1\right|=3\)
\(\Rightarrow\orbr{\begin{cases}x-1=3\\x-1=-3\end{cases}}\)
mà \(x+1< 0\)
\(\Rightarrow x-1=-3\)
\(\Rightarrow x=-2\)
q) \(\left(x-2\right)\left(x+4\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-2=0\\x+4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=-4\end{cases}}}\)
hok tốt!!
31x72 - 31x70 - 31 x 2 - 31
=31x(72 -70 -2 -1)
=31 x (-1)
= -31
những câu sau thì lam tương tự nha bạn ^_^
1 a x=4
b x=-4
c x=-7
d x=3
e x=10
g x=60
h x=36
i x=16
2a 1,2,3,4,5,6,7,8,9
b 1,2,3,4,5,6,7,8,9.........
c rỗng
3a 0
b 0
c10
3x=234—> 243 chứ bạn
3x=243
Vì 35=243
Nên x=5
3x=4096
6x=216
Vì 63=216
Nên x=3
5.3x=405
3x=405:5
3x=81
Vì 34=81
Nên x=4
2x=4
Vì 22=4
Nên x=2
x5=32
Vì 25=32
Nên x=5
x4=81
Vì 34=81 và (-3)4=81
Nên x=3 hoặc x=-3
(x—2)5=243
(x—2)5=35
Nên x—2=3
x=3+2
x=5
(x—1)4=16
(x—1)4=24
Nên x—1 =2 hoặc x—1=-2
x=2+1 hoặc x=-2 +1
x=3 hoặc x=-1
(x+1)3=125
(x+1)3=53
Nên x+1=3
x=3-1
x=1
(x—2)3=64
(x—2)3=43
Nên x—2=4
x=4+2
x=6
(x—1)5=32
(x—1)5=25
==> x—1=5
x=5+1
x=6
\(3^x=243\Rightarrow3^x=3^5\Rightarrow x=5\)
câu thứ 2 mn chịu
\(6^x=216\Rightarrow6^x=6^3\Rightarrow x=3\)
\(5.3^x=405\\ 3^x=405:5\\ 3^x=81\\ \Rightarrow3^x=3^4\\ \Rightarrow x=4\)
\(2^x=4\\ \Rightarrow2^x=2^2\\ \Rightarrow x=2\)
\(x^5=32\\ \Rightarrow x^5=2^5\\ \Rightarrow x=2\)
câu 7 mn ko hỉu
\(x^4=81\\ x^4=\left(+-3\right)^4\\ x=+-3\)
câu 9 mn chịu
TL:
a.\(2^6.2^n=2^{11}\)
\(2^{6+n}=2^{11}\)
\(\Rightarrow n=5\)
b. \(3^7:3^n=3^4\)
\(3^{7-n}=3^4\)
\(\Rightarrow n=3\)
c.\(2^n.32=2^{10}\)
\(2^{n+5}=2^{10}\)
\(\Rightarrow n=5\)
32.(x-10)=32
=>x-10=32:32
=>x-10=1
=>x=11
(x-78).26=0
=>x-78=0:26
=>x-78=0
=>x=78
(x-14):2=3
=>x-14=3.2
=>x-14=6
=>x=14+6
=>x=20
a) 32.(x-10)=32
x-10=1
x=11
b) (x-78).26=0
x-78=0
x=78
c) (x-14):2=3
x-14=6
x=20
\(\dfrac{x-3}{32}=\dfrac{-2}{3-x}\)
\(\Rightarrow\dfrac{x-3}{32}=\dfrac{-\left(-2\right)}{-\left(3-x\right)}\)
\(\Rightarrow\dfrac{x-3}{32}=\dfrac{2}{x-3}\)
\(\Rightarrow\left(x-3\right)^2=64\)
\(\Rightarrow\left[{}\begin{matrix}x-3=8\\x-3=-8\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=11\\x=-5\end{matrix}\right.\)
\(x-\dfrac{3}{32}=-\dfrac{2}{3}-x\\ \Rightarrow x-\dfrac{3}{32}+x=-\dfrac{2}{3}\\ \Rightarrow2x=-\dfrac{55}{96}\\ \Rightarrow x=-\dfrac{55}{192}.\)