Tìm số tự nhiên x biết
A) ( 3x - 15 )^7 = 0
B) 4^2x-6 = 1
C) ( 3 - x ) ^10x : ( 3 - x ) ^ 20 = 1
D) ( x - 6 )^ 3 = ( x - 6 ) ^2
Bài 3:Tìm x:
a) (3.x-15)7= 0
b) 42 . x + 6=1
c) (3-x)10x: (3-x)20= 1 ( x ≠ 3)
d) (x-6)3=(x-6)2
Giusp minh nah
a) (3x-15)7 = 0
3x-15 = 0
3x = 0+15
3x = 15
x = 15:3
x = 5
b) 42x-6 = 1
2x-6 = 0
2x = 0+6
2x = 6
x = 6:2
x = 3
c) Tớ ko bít
d) (x - 6)3 = (x - 6)2
Th1:
x - 6 = 1
x = 1 + 6
x = 7
Th2:
x - 6 = 0
x = 6
Vậy x = 7
x = 6
--thodagbun--
a, (3x-15)^7=0 <=> 3x-15=0 <=> x=5
b, 42x+6=1 <=> 16x=-5 <=>x=-5/16
c, \(\dfrac{\left(3-x\right)^{10x}}{\left(3-x\right)^{20}}=1\Leftrightarrow\left(3-x\right)^{10x-20}=1\)
TH1: 10x-20 = 0 <=> x=2
TH2: 3-x=1 <=> x=2
Vậy x=2
d, (x-6)^3 = (x-6)^2
<=> (x-6)^2.[(x-6)-1]=0
<=> (x-6)^2=0 hoặc (x-6)-1=0
<=> x=6 hoặc x=7
Tìm x biết :
a) (3x-15^7)=0
b) 4^2x-6=1
c) (3-x)^10x:(3-x)^20=1 (x#3)
d) (x-6)^3=(x-6)^2
1. Tìm 1 số tự nhiên x,biết
a.7*7x+1=343
b.23*2x=64
c.(3x-15)7=0
d.4(2x-6)=1
e.(3-x)10x:(3-x)20=1 (x khác 3)
f.(x-6)3=(x-6)2
a, 7.7x+1=343
7x+1+1=343
7x+2=343=73
=> x+2=3
x=3-2=1
b,23.2x=64
23+x=64=26
=> 3+x=6
x=6-3=3
c,(3x-15)7=0
=> (3x-15)=0
3x-15=0
3x=0+15
3x=15
x=15:3=5
d, 4(2x-6)=1
=> 4(2x-6)=40=1
=> 2x-6=0
2x=0+6=6
x=6:2=3
e, (3-x)10x:(3-x)20=1
Nx: Một số chia cho chính nó luôn bằng1
Có: 3-x=3-x
=> 10x=20
x=20:10=2
f, (x-6)3=(x-6)2
Ta có: Th1: 03=02=0
=> (x-6)3=(x-6)2=0
=> x-6 =0
x=0+6=6
Th2: 13=12=1
=> (x-6)3=(x-6)2=1
=> x-6=1
x=1+6=7
tìm x,biết:
a. (3x-15)^7=0
b.4^2x-6=1
c. (3-x)^10x:(3-x)^20x=1
d.(x-6)^3=(x-6)^2
1. Tìm số tự nhiên x biết 1) 3^x . 3=243 2) 7.2^x=56 3) x^3=8 4)x^20=x 5) 2^x-15=17 6) (2x+1)^3=9.81 7) x^6:x^3=115 8) ( 2x-15)^5=(2x-15)^3 9) 3^x+2-5.3^x=36 10) 7.4^x-1+4^x+1=23 Giúp tớ bài này với
1: =>3^x=81
=>x=4
2: =>2^x=8
=>x=3
3: =>x^3=2^3
=>x=2
4: =>x^20-x=0
=>x(x^19-1)=0
=>x=0 hoặc x=1
5: =>2^x=32
=>x=5
6: =>(2x+1)^3=9^3
=>2x+1=9
=>2x=8
=>x=4
7: =>x^3=115
=>\(x=\sqrt[3]{115}\)
8: =>(2x-15)^5-(2x-15)^3=0
=>(2x-15)^3*[(2x-15)^2-1]=0
=>2x-15=0 hoặc (2x-15)^2-1=0
=>2x-15=0 hoặc 2x-15=1 hoặc 2x-15=-1
=>x=15/2 hoặc x=8 hoặc x=7
1. Tìm số tự nhiên x biết:
1) \(3^x.3=243\)
\(3^x=243:3\)
\(3^x=81\)
\(3^x=3^4\)
\(\Rightarrow x=4\)
_____
2) \(7.2^x=56\)
\(2^x=56:7\)
\(2^x=8\)
\(2^x=2^3\)
\(\Rightarrow x=3\)
_____
3) \(x^3=8\)
\(x^3=2^3\)
\(\Rightarrow x=3\)
_____
4) \(x^{20}=x\)
\(x^{20}-x=0\)
\(x\left(x^{19}-1\right)=0\)
\(\Rightarrow x=0\) hoặc \(x=1\)
5) \(2^x-15=17\)
\(2^x=17+15\)
\(2^x=32\)
\(2^x=2^5\)
\(\Rightarrow x=5\)
_____
6) \(\left(2x+1\right)^3=9.81\)
\(\left(2x+1\right)^3=729=9^3\)
\(\rightarrow2x+1=9\)
\(2x=9-1\)
\(2x=8\)
\(x=8:2\)
\(\Rightarrow x=4\)
_____
7) \(x^6:x^3=125\)
\(x^3=125\)
\(x^3=5^3\)
\(\Rightarrow x=5\)
_____
8) \(\left(2x-15\right)^5=\left(2x-15\right)^3\)
\(\rightarrow\left(2x-15\right)^5-\left(2x-15\right)^3=0\)
\(\left(2x-15\right)^3.\left[\left(2x-15\right)^2-1\right]=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(2x-15\right)^3=0\\\left(2x-15\right)^2-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{15}{2}\\x=7\\x=8\end{matrix}\right.\)
_____
9) \(3^{x+2}-5.3^x=36\)
\(3^x.\left(3^2-5\right)=36\)
\(3^x.\left(9-5\right)=36\)
\(3^x.4=36\)
\(3^x=36:4\)
\(3^x=9\)
\(3^x=3^2\)
\(\Rightarrow x=2\)
_____
10) \(7.4^{x-1}+4^{x+1}=23\)
\(\rightarrow7.4^{x-1}+4^{x-1}.4^2=23\)
\(4^{x-1}.\left(7+4^2\right)=23\)
\(4^{x-1}.\left(7+16\right)=23\)
\(4^{x-1}.23=23\)
\(4^{x-1}=23:23\)
\(4^{x-1}=1\)
\(4^{x-1}=4^1\)
\(\rightarrow x-1=0\)
\(x=0+1\)
\(\Rightarrow x=1\)
Chúc bạn học tốt
Tìm x , Biết
a) (x-4) x - (x-3)^2=0
b) 3x-6 = x^2-16
c) (2x-3)^2 - 49=0
d) 2x (x-5) - 7 (5-x)=0
a) \(\Leftrightarrow x^2-4x-x^2+6x-9=0\\ \Leftrightarrow2x=9\\ \Leftrightarrow x=4,5\)
b) \(\Leftrightarrow x^2-3x-10=0\\ \Leftrightarrow\left(x^2+2x\right)-\left(5x+10\right)=0\\ \Leftrightarrow x\left(x+2\right)-5\left(x+2\right)=0\\ \left(x-5\right)\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)
c) \(\Leftrightarrow\left(2x-3-7\right)\left(2x-3+7\right)=0\\ \Leftrightarrow\left(2x-10\right)\left(2x+4\right)=0\\ \Leftrightarrow\left(x-5\right)\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)
d) \(\Leftrightarrow\left(2x+7\right)\left(x-5\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{7}{2}\\x=5\end{matrix}\right.\)
Tìm x biết (3x-15)7=0 ;42x-6=1 ;(3-x)10x/(3-x)20=1(x khác 3) (x-6)3=(x-6)2
(3x - 15)7 = 0
=> 3x - 15 = 0
=> 3x = 15
=> x = 5
42x-6 = 40
=> 2x - 6 = 0
=> 2x = 6
=>x = 3
Bài toán 3 : Tìm x, biết.
a. 2(x – 5) – 3(x + 7) = 14 b. 5(x – 6) – 2(x + 3) = 12
c. 3(x – 4) – (8 – x) = 12 d. -7(3x – 5) + 2(7x – 14) = 28
e. 5(3 – 2x) + 5(x – 4) = 6 – 4x f. -5(2 – x) + 4(x – 3) = 10x – 15
g. 2(4x – 8) – 7(3 + x) = |-4|(3 – 2) h. 8(x – |-7|) – 6(x – 2) = |-8|.6 – 50
k. -7(5 – x) – 2(x – 10) = 15 l. 4(x – 1) – 3(x – 2) = -|-5|
m. -4(x + 1) + 89x – 3) = 24 n. 5(x – 30 – 2(x + 6) = 9
o. -3(x – 5) + 6(x + 2) = 9 p. 7(x – 9) – 5(6 – x) = – 6 + 11x
q. 10(x – 7) – 8(x + 5) = 6.(-5) + 24
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
d, \(-7\left(3x-5\right)+2\left(7x-14\right)=28\)
\(\Leftrightarrow-21x+35+14x-28=28\Leftrightarrow-7x=21\Leftrightarrow x=-3\)
e, \(5\left(3-2x\right)+5\left(x-4\right)=6-4x\)
\(\Leftrightarrow15-6x+5x-20=6-4x\Leftrightarrow-5-x=6-4x\)
\(\Leftrightarrow-11+3x=0\Leftrightarrow x=\frac{11}{3}\)
f, \(-5\left(2-x\right)+4\left(x-3\right)=10x-15\)
\(\Leftrightarrow-10+5x+4x-12=10x-15\Leftrightarrow-22+9x=10x-15\)
\(\Leftrightarrow-7-x=0\Leftrightarrow x=-7\)
Tìm các số tự nhiên x và y , sao cho :
a) (2x+1)(y-3)=10 b) (3x-2)(2y-3)=1
c) (x+1)(2y-1)=12 d) x+6=y(x-1)
e) x-3=y(x+2)