Tìm x biết 2 3 x = - 1 8
A. x = -1/4
B. x = -5/16
C. x = 3/16
D. x = -3/16
3). Tìm số tự nhiên x ,biết a)2^x =4 b) 2^x=1 c) 2^x=16 d) 3^x=9 e) 5^x=125 f) 8^x=64 h) 3^x+1=3^2
3) Tìm số tự nhiên x, biết:
a) \(2^x=4\)
\(2^x=2^2\)
\(\Rightarrow x=2\)
___________
b) \(2^x=1\)
\(2^x=2^0\)
\(\Rightarrow x=0\)
___________
c) \(2^x=16\)
\(2^x=2^4\)
\(\Rightarrow x=4\)
___________
d) \(3^x=9\)
\(3^x=3^2\)
\(\Rightarrow x=2\)
___________
e) \(5^x=125\)
\(5^x=5^3\)
\(\Rightarrow x=3\)
___________
f) \(8^x=64\)
\(8^x=8^2\)
\(\Rightarrow x=2\)
___________
h) \(3^{x+1}=3^2\)
\(\rightarrow x+1=2\)
\(x=2-1\)
\(x=1\)
\(\Rightarrow x=1\)
Chúc bạn học tốt
a: 2^x=4
=>2^x=2^2
=>x=2
b: 2^x=1
=>2^x=2^0
=>x=0
c: 2^x=16
=>2^x=2^4
=>x=4
d; 3^x=9
=>3^x=3^2
=>x=2
e: 5^x=125
=>5^x=5^3
=>x=3
f: 8^x=64
=>8^x=8^2
=>x=2
f: 3^x+1=3^2
=>x+1=2
=>x=1
Tìm số nguyên x, biết:
a) 3 - x = 25 -(-4)
b) x - 10 = (-8) -6
c) x + (-4) = 1 - 9
d) (-5) + x = 16 + (-8)
Tìm x, biết: a) x = 1/4 + 5/13 b) x/3 = 2/3 + -1/7 c) x/3 = 16/24 + 24/ 36
d) x/15 = 1/5 + 2/3
\(a)x=\dfrac{1}{4}+\dfrac{5}{13}=\dfrac{33}{52}.\\ b)\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}.\\ \Leftrightarrow\dfrac{x}{3}=\dfrac{11}{21}.\\ \Leftrightarrow\dfrac{7x}{21}=\dfrac{11}{21}.\\ \Rightarrow7x=11.\\ \Leftrightarrow x=\dfrac{11}{7}.\\ c)\dfrac{x}{3}=\dfrac{16}{24}+\dfrac{24}{36}=\dfrac{2}{3}+\dfrac{2}{3}=\dfrac{4}{3}.\\ \Rightarrow x=4.\\ d)\dfrac{x}{15}=\dfrac{1}{5}+\dfrac{2}{3}=\dfrac{13}{15}.\\ \Rightarrow x=13.\)
Tìm x, biết:
a) x × 5 = 35 – 5
b) x : 4 = 12 – 8
c) 4 × x = 6 × 2
d) x : 3 = 16 : 4
a) x × 5 = 35 – 5
x × 5 = 30
x = 30 : 5
x = 6
b) x : 4 = 12 – 8
x : 4 = 4
x = 4 × 4
x = 16
c) 4 × x = 6 × 2
4 × x = 12
x = 12 : 4
x = 3
d) x : 3 = 16 : 4
x : 3 = 4
x = 4 × 3
x = 12
Tìm x‚ biết:
a) [(-0.5)^3] = 1/64
b) 7^x+2 + 2×7^x-1 = 345
c) 3^x+1 + 3^x+3 = 810
d) 8^x × 16^-2x = 4^5
Tìm x, biết:
a) x + 99:3 = 55
b) (x - 25): 15=20
c) (3.x - 15).7 = 42
d) (8x - 16)(x-5)=0
e) x.(x+1)=2+4+6+8+10+...+2500
a, \(x\) + 99: 3 = 55
\(x\) + 33 = 55
\(x\) = 55 - 33
\(x\) = 22
b, (\(x\) - 25):15 = 20
\(x\) - 25 = 20 x 15
\(x\) - 25 = 300
\(x\) = 300 + 25
\(x\) = 325
c, (3\(x\) - 15).7 = 42
3\(x\) - 15 = 42:7
3\(x\) - 15 = 6
3\(x\) = 6 + 15
3\(x\) = 21
\(x\) = 21: 3
\(x\) = 7
d, (8\(x\) - 16).(\(x\) -5) = 0
\(\left[{}\begin{matrix}8x-16=0\\x-5=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}8x=16\\x=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=16:8\\x=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=2\\x=5\end{matrix}\right.\)
Vậy \(x\) \(\in\) {2; 5}
Tìm x, biết:
A, -16 + 23 + x = -16
B, 10 – 2 ( 4 – 3x ) = -4
C, -12 + 3 ( -x + 7 ) = -18
D, 24 : ( 3x – 2 ) = -3
E, | x + 8 | – 7 = 8
F, -45 : 5 nhân ( -3 – 2x ) = 3
G, | x – 1 | = 0
H, -13 nhân | x | = -26
A,-16+23+x=-16
<=>x=-16+16-23
<=>x=-23
B,10-2(4-3x)=-4
<=>10-8+6x=-4
<=>6x=-4-10+8
<=>6x=-6
<=>x=-1
C,-12+3(-x+7)=-18
<=>-12-3x+21=-18
<=>-3x=-18+12-21
<=>-3x=-27
<=>x=9
D,24:(3x-2)=-3
<=>24/(3x-2)=-3
<=>-3(3x-2)=24
<=>3x-2=-8
<=>3x=-6
<=>x=-2
E,|x+8|-7=8
<=>|x+8|=15
<=>x+8=+-15
Chia 2 TH:
TH1:x+8=15
<=>x=7
TH2:x+8=-15
<=>x=-23
F,-45:5(-3-2x)=3
<=>-9(-3-2x)=3
<=>27+18x=3
<=>18x=-24
<=>x=-4/3
G,|x-1|=0
<=>x-1=0
<=>x=1
H,-13|x|=-26
<=>|x|=2
<=>x=+-2
a) -16 + 23 + x = -16
x = -16 + 16 - 23
x = -23
Vậy x = -23
b) 10 - 2. (4 - 3x) = -4
10 - 2 . 4 + 2. 3x = -4
10 - 8 + 6x = -4
6x = -4 - 10 + 8
6x = -6
x = (-6) : 6
x = -1
Vậy x = -1
c) -12 + 3. (-x + 7) = -18
-12 + 3. (-x) + 3. 7 = -18
-12 + (-3x) + 21 = -18
-3x = -18 + 12 - 21
-3x = -27
x = (-27) : (-3)
x = -9
Vậy x = -9
d) 24 : (3x - 2) = -3
3x - 2 = 24 : (-3)
3x - 2 = -8
3x = -8 + 2
3x = -6
x = (-6) : 3
x = -2
Vậy x = -2
e) lx + 8l - 7 = 8
lx + 8l = 8 + 7
lx + 8l = 15
\(\Rightarrow\hept{\begin{cases}x+8=15\\x=18-5\\x=13\end{cases}hay\hept{\begin{cases}x+8=-15\\x=-15-8\\x=-23\end{cases}}}\)
Vậy \(x\in\left\{13;-23\right\}\)
f) (-45) : 5. (-3 - 2x) = 3
(-9). (-3 - 2x) = 3
(-9). (-3) + 9. 2x = 3
27 + 18x = 3
18x = 3 - 27
18x = -24
x = (-24) : 18
x =\(\frac{-4}{3}\)
Vậy x =\(\frac{-4}{3}\)
g) lx - 1l = 0
\(\Rightarrow x-1=0\)
x = 0 + 1
x = 1
Vậy x = 1
h) (-13). lxl = -26
lxl = (-26) : (-13)
lxl = 2
\(\Rightarrow x=2\)
Vậy x = 2
Chúc bạn học tốt!!!
Bài 1 tìm x
a)30+X=120÷5+27
b)40-3×X=13
c)2×X-8=16
d)1/2×X-1/3=1/4
Giúp em với ạ
\(a,30+X=120:5+27\\ 30+X=24+27\\ 30+X=51\\ X=51-30=21\\ ---\\ b,40-3\times X=13\\ 3\times X=40-13=27\\ X=\dfrac{27}{3}=9\\ ---\\ 2\times X-8=16\\ 2\times X=16+8\\ 2\times X=24\\ X=\dfrac{24}{2}=12\\ \\---\\ \dfrac{1}{2}\times X-\dfrac{1}{3}=\dfrac{1}{4}\\ \dfrac{1}{2}\times X=\dfrac{1}{4}+\dfrac{1}{3}=\dfrac{7}{12}\\ X=\dfrac{7}{12}:\dfrac{1}{2}=\dfrac{7}{6}\)
a.30+X=24+27
30+X=51
X=51-30
X=21
b.3xX=40-13
3xX=27
X=27:3=9
C.2xX=16+8
2xX=24
X=24:2=12
D.1/2xX=1/3+1/4
1/2xX=7/12
X=7/12:1/2=7/6
a) \(30+x=120:5+27\)
\(30+x=24+27\)
\(30+x=51\)
\(x=51-30\)
\(x=21\)
_____
b) \(40-3\times x=13\)
\(3\times x=40-13\)
\(3\times x=27\)
\(x=27:3\)
\(x=9\)
______
c) \(2\times x-8=16\)
\(2\times x=16+8\)
\(2\times x=24\)
\(x=24:2\)
\(x=12\)
______
d) \(\dfrac{1}{2}\times x-\dfrac{1}{3}=\dfrac{1}{4}\)
\(\dfrac{1}{2}\times x=\dfrac{1}{4}+\dfrac{1}{3}\)
\(\dfrac{1}{2}\times x=\dfrac{7}{12}\)
\(x=\dfrac{7}{12}:\dfrac{1}{2}=\dfrac{7}{12}\times2\)
\(x=\dfrac{7}{6}\)
2 tính : a) 1+1/4+1/8+1/16 =
=
b) 2-1/8-1/12-1/16 =
=
c) 4/99 x 18/5 : 12/11 + 3/5 =
=
d) ( 1-3/4 ) x ( 1+ 1/3 ) : ( 1- 1/3 ) =
=
a) 1 + 1/4 + 1/8 + 1/16
= 16/16 + 4/16 + 2/16 + 1/16
= 23/16
b) 2 - 1/8 - 1/12 - 1/16
= 96/48 - 6/46 - 4/48 - 3/48
= 83/48
c) 4/99 × 18/5 : 12/11 + 3/5
= 8/55 : 12/11 + 3/5
= 2/15 + 3/5
= 2/15 + 9/15
= 11/15
d) (1 - 3/4) × (1 + 1/3) : (1 - 1/3)
= 1/4 × 4/3 : 2/3
= 1/3 : 2/3
= 2
1 + 1/4 + 1/8 + 1/16
= 16 + 4 + 2 + 1 / 16
=23/16
2-1/8-1/12-1/16
= 96 - 6 - 4 - 3 / 48
= 83 / 48
4/99 x 18/5 : 12 /11 + 3/5
= 4/99 x 18/5 x 11/12 + 3/5
= 2/15 + 3/5
= 11/15
(1 - 3/4) x (1+1/3) : (1-1/3)
= 1/4 x 4/3 : 2/3
= 1/4 x 4/3 x 3/2
= 1/2
Tìm số tự nhiên x, biết
a) ( x + 1 ) 2 = 16
b) ( x + 1 ) 3 = 27
c) ( x + 1 ) 3 = 16
d) ( 2 . x - 1 ) 3 = 125 .