tìm x,biết
(4/9)^x = (3/27)^2
hlep me
1>tìm n thuộc N biết:
27^n . 9^n = 9^27 : 81
2>Tìm x biết:
a)(x- 1/2)^3 = 1/27
b)(x + 1/2)^2 = 4/25
tìm số nguyên x , biết :
a) x + 546 = 46
b) 2x - 19 x 3 = 27
c) x + 12= 23 + 3 x 3^4
d) x- 12 = 3 - 3 x 2^4
e) ( 27 - x ) nhân ( x +9 ) = 0
f) ( -x) x ( x-43) = 0
a) \(x+546=46\\ x=46-546\\ x=-500\)
b) \(2x-19\times3=27\\ 2x-57=27\\ 2x=27+57\\ 2x=84\\ x=84:2\\ x=42\)
c) \(x+12=23+3\times3^4\\ x+12=23+3\times81\\ x=23+243-12\\ x=254\)
d) \(x-12=3-3\times2^4\\ x-12=3-3\times16\\ x=3-48+12\\ x=-33\)
e) \(\left(27-x\right)\left(x+9\right)=0\\ \Rightarrow\left[{}\begin{matrix}27-x=0\\x+9=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=27\\x=-9\end{matrix}\right.\)
f) \(\left(-x\right)\left(x-43\right)=0\\ \Rightarrow\left[{}\begin{matrix}-x=0\\x-43=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=43\end{matrix}\right.\)
a) x + 546 = 46
x = 46 - 546
x = -500
b) 2x - 19 x 3 = 27
2x - 57 = 27
2x = 27 + 57
2x = 84
x = 84 : 2
x = 42
c) x + 12 = 23 + 3 x 34
x + 12 = 23 + 3 x 81
x + 12 = 23 + 243
x + 12 = 266
x = 266 - 12
x = 254
d) x - 12 = 3 - 3 x 24
x - 12 = 3 - 3 x 16
x - 12 = 3 - 48
x - 12 = -45
x = -45 + 12
x = -33
e) (27 - x) x (x + 9) = 0
TH1: 27 - x = 0
x = 27 - 0
x = 27
TH2: x + 9 = 0
x = 0 + 9
x = 9
⇒ x = 27 hoặc x = 9
f) (-x) x (x - 43) = 0
TH1: -x = 0
⇒ x = 0
TH2: x - 43 = 0
x = 0 + 43
x = 43
⇒ x = 0 hoặc x = 43.
Tìm x, biết:
1,27x.9x=927:81
2,(-3)x-2=-275.94
1, 27x.9x=927:81
(33)x.(32)X=(32)27:34
33X.32X=354:34
33X+2X=350
35X=350
Suy ra :5x=50
x=10
tìm x biết (x+3)(x^2-3x+9)-x(x^2-9)=27
\(\left(x+3\right)\left(x^2-3x+9\right)-x\left(x^2-9\right)=27\\ x.x^2-x.3x+x.9-x.x^2+x.9=27\\ x^3-3x^2+9x-x^3+9x=27\\ 3x^2+18x=27\\ 21x^2=27\\ x^2=\dfrac{9}{7}\\ \Rightarrow x=\sqrt{\dfrac{9}{7}}\)
\(\left(x+3\right)\left(x^2-3x+9\right)-x\left(x^2-9\right)=27\\ x.x^2-x.3x+x.9+3.x^2-3.3x+3.9-x.x^2+x.9=27\\ x^3-3x^2+9x+3x^2-9x+27-x^3+9x=27\\ 9x+27=27\\ 9x=0\\ x=0\)
Tìm x biết : a) x+3/22=-27/121.11/9 b) (3và2/20-2và1/20)x+2/7=3/5 c) |3/2x-5|-1/2=-1/4
a) x+3/22=-27/121.11/9
⇒ x+3/22=-3/11
⇒ x=-9/22
b) (3/2/20-2/1/20)x+2/7=3/5
⇒ (31/10-41/20)x=11/35
⇒ 21/20x=11/35
⇒x=44/147
c) |3/2x-5|-1/2=-1/4
⇒ |3/2x-5|=1/4
⇒ hoặc 3/2x-5=1/4⇒3/2x=21/4⇒x=7/2
hoặc 3/2x-5=-1/4⇒3/2x=19/4⇒x=19/6
tìm x, biết:
a. 2 . 3x - 405 = 3^x - 1
b.(1/81)^x . 27^2x = (-9)^4
hepl me
tìm x biết x thuộc n
27 . ( 3x + 39 ) 27 ( 4x -1 )
20 - ( x + 14 ) = 15
24 + 3 ( 5 - x ) = 27
câu đầu bạn viết lại đề bài nhé , mình vẫn chưa rõ
2. 20-(x+14)=15
x+14=5
x=-11 ( vì x thuộc n , loại )
x thuộc rỗng
3.24+3(5-x)=27
3(5-x)=3
5-x=1
x=4 (chọn )
tìm x biết
\(\dfrac{7}{9}:\left(2+\dfrac{3}{4}.x\right)+\dfrac{5}{9}=\dfrac{23}{27}\)
|x|\(-\dfrac{3}{4}=\dfrac{5}{3}\)
\(\left|2.x-\dfrac{1}{3}\right|+\dfrac{5}{6}=1\)
giúp mk vs nhanh lên mình đang bận
b) Ta có: \(\left|x\right|-\dfrac{3}{4}=\dfrac{5}{3}\)
\(\Leftrightarrow\left|x\right|=\dfrac{5}{3}+\dfrac{3}{4}=\dfrac{20}{12}+\dfrac{9}{12}=\dfrac{29}{12}\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{29}{12}\\x=-\dfrac{29}{12}\end{matrix}\right.\)
c) Ta có: \(\left|2x-\dfrac{1}{3}\right|+\dfrac{5}{6}=1\)
\(\Leftrightarrow\left|2x-\dfrac{1}{3}\right|=\dfrac{1}{6}\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-\dfrac{1}{3}=\dfrac{1}{6}\\2x-\dfrac{1}{3}=\dfrac{-1}{6}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{1}{6}+\dfrac{1}{3}=\dfrac{1}{2}\\2x=\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{4}\\x=\dfrac{1}{12}\end{matrix}\right.\)
tìm x biết (4/9)x+1=(8/27)^6
\(\left(\dfrac{4}{9}\right)^{x+1}=\left(\dfrac{8}{27}\right)^6\)
\(\Leftrightarrow\left(\dfrac{2}{3}\right)^{2x+2}=\left(\dfrac{2}{3}\right)^{18}\)
\(\Leftrightarrow2x+2=18\Leftrightarrow2x=16\Leftrightarrow x=8\)
tìm x biết (4/9)x+1=(8/27)^6