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a: \(4x^3+12=120\)
=>\(4x^3=108\)
=>\(x^3=27=3^3\)
=>x=3
b: \(\left(x-4\right)^2=64\)
=>\(\left[{}\begin{matrix}x-4=8\\x-4=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-4\end{matrix}\right.\)
c: (x+1)^3-2=5^2
=>\(\left(x+1\right)^3=25+2=27\)
=>x+1=3
=>x=2
d: 136-(x+5)^2=100
=>(x+5)^2=36
=>\(\left[{}\begin{matrix}x+5=6\\x+5=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-11\end{matrix}\right.\)
e: \(4^x=16\)
=>\(4^x=4^2\)
=>x=2
f: \(7^x\cdot3-147=0\)
=>\(3\cdot7^x=147\)
=>\(7^x=49\)
=>x=2
g: \(2^{x+3}-15=17\)
=>\(2^{x+3}=32\)
=>x+3=5
=>x=2
h: \(5^{2x-4}\cdot4=10^2\)
=>\(5^{2x-4}=\dfrac{100}{4}=25\)
=>2x-4=2
=>2x=6
=>x=3
i: (32-4x)(7-x)=0
=>(4x-32)(x-7)=0
=>4(x-8)*(x-7)=0
=>(x-8)(x-7)=0
=>\(\left[{}\begin{matrix}x-8=0\\x-7=0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=8\\x=7\end{matrix}\right.\)
k: (8-x)(10-2x)=0
=>(x-8)(x-5)=0
=>\(\left[{}\begin{matrix}x-8=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=5\end{matrix}\right.\)
m: \(3^x+3^{x+1}=108\)
=>\(3^x+3^x\cdot3=108\)
=>\(4\cdot3^x=108\)
=>\(3^x=27\)
=>x=3
n: \(5^{x+2}+5^{x+1}=750\)
=>\(5^x\cdot25+5^x\cdot5=750\)
=>\(5^x\cdot30=750\)
=>\(5^x=25\)
=>x=2
18 - 4\(x\) = -20 - 6\(x\)
-4\(x\) + 6\(x\) = - 20 - 18
2\(x\) = - 38
\(x\) = - 19
h, -15 \(\times\) 24 = -7\(x\) + 32
7\(x\) = 360 + 32
7\(x\) = 392
\(x\) = 392:7
\(x\) = 56
i, 15\(x\) -3.(4\(x\) - 6) = -12 + 36
15\(x\) - 12\(x\) + 18 = 24
3\(x\) = 24 - 18
3\(x\) = 6
\(x\) = 2
k, -10\(x\) - 27 = -7\(x\) + 33
-27 - 33 = -7\(x\) + 10\(x\)
3\(x\) = -60
\(x\) = -20
18x -19 = 21 + 8x
18 x - 8x = 21 + 19
10 x = 40
x =4
g) 18 -4x=-20-6x
-4x + 6x = -20 - 18
2x = -38
x= -19
k, -10 \(x\) - 27 = -7\(x\) + 33
-27 - 33 = -7\(x\) + 10\(x\)
3\(x\) = -60
\(x\) - 20
m, -17\(x\) - 24 = -9\(x\) - 40
-24 + 40 = -9\(x\) + 17\(x\)
8\(x\) = 16
\(x\) = 2
tìm x,biết
5-x-16=40+x
4x-10=15-x
15-x=4x-5
x-15=6+4x
-12+x=5x-20
7x-4=20+3x
5x-7=-21-2x
x+15=20-4x
17-x=7-6x
Bài 6. Tìm x ϵ N biết
a) (x –15) .15 = 0
b) 32 (x –10 ) = 32
c) ( x – 5)(x – 7) = 0
d) (x – 35).35 = 35
5x-16=40+x
4x-10=15-x
-12+x=5x-20
7x-4=20+3x
5x-7=-21-2x
x+15=7-6x
AI GIẢI NHANH ĐÚNG MÌNH CHỌN NHAA
+ \(5x-16=40+x\)
⇒ \(5x-x=40+16\)
⇒ \(4x=56\)
⇒ \(x=\frac{56}{4}\)
⇒ \(x=16\)
+ \(4x-10=15-x\)
⇒ \(4x+x=15+10\)
⇒ \(5x=25\)
⇒ \(x=\frac{25}{5}\)
⇒ \(x=5\)
+ \(-12+x=5x-20\)
⇒ \(x-12=5x-20\)
⇒ \(x=5x-20+12\)
⇒ \(x=5x-32\)
⇒ \(5x-x=32\)
⇒ \(4x=32\)
⇒ \(x=\frac{32}{4}\)
⇒ \(x=8\)
+ \(7x-4=20+3x\)
⇒ \(7x-3x=20+4\)
⇒ \(4x=24\)
⇒ \(x=\frac{24}{4}\)
⇒ \(x=6\)
+ \(5x-7=-21-2x\)
⇒ \(5x+2x=-21+7\)
⇒ \(7x=14\)
⇒ \(x=\frac{14}{7}\)
⇒ \(x=2\)
+ \(x+15=7-6x\)
⇒ \(x+6x=7-15\)
⇒ \(7x=-8\)
⇒ \(x=-\frac{8}{7}\)
Bài làm :
\(a,\left(7x-7\right)\left(x-3\right)=0\)
\(\Rightarrow\orbr{\begin{cases}7x-7=0\\x-3=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\x=3\end{cases}}\)
Vậy x = 1 hoặc x = 3 .
\(b,108-18x=54\)
\(18x=108-54\)
\(18x=54\)
\(x=54:18\)
\(x=3\)
\(c,35.\left(x-10\right)=35\)
\(x-10=35:35\)
\(x-10=1\)
\(x=1+10\)
\(x=11\)
\(d,3x+5x=40\)
\(\left(3+5\right)x=40\)
\(8x=40\)
\(x=40:8\)
\(x=5\)
Học tốt
a. ( 7x - 7 ) ( x - 3 ) = 0
<=>\(\orbr{\begin{cases}7x-7=0\\x-3=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=1\\x=3\end{cases}}\)
b. 108 - 18x = 54
=> 18x = 54
=> x = 3
c. 35 ( x - 10 ) = 35
=> x - 10 = 1
=> x = 11
d. 3x + 5x = 40
=> 8x = 40
=> x = 5