a) 3.2\(^x\)- 3 = 45
b) ( 2\(^x\)+ 1 )\(^3\)= 125
c) ( 90 : 15)\(^2\)+ x = 2\(^6\)- 2 \(^2\)x 7
d) 1990\(^0\)+ ( x - 15 ) = 3\(^{199}\): 3\(^{196}\)- 1 \(^{2000}\)
nhanh nhe mk gan di hoc rui
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d)19900+(x-15)=3199:3196-12000
1+(x-15)=26
x-15=26-1=25
x=25+15=40
c) (90:15)2+x=26-22.7
36+x=-16320
x=-16320-36=-16356
b) (2x+1)3=125
(2x+1)3=53
2x+1=5
2x=5-1=4=22
x=2
a) ko hiểu đề bài
a) \(3.2^x-3=45\)
\(3\left(2^x-1\right)=45\)
\(2^x-1=15\)
\(2^x=15+1\)
\(2^x=16\)
\(2^x=2^4\)
=>x=4
b) \(\left(2^x+1\right)^3=125\)
\(\left(2^x+1\right)^3=5^3\)
=> \(2^x+1=5\)
Làm tương tự câu a, đc x = 2
c) \(\left(90:15\right)^2+x=2^6-2^{2.7}\)
\(6^2+x=64-16384\)
\(x=-16320-36\)
x=-16356
d) \(1990^0+\left(x-15\right)=3^{199}:3^{196}-1^{2000}\)
1 + x - 15 = 33-1
x= 27-1-1+15
x=40
a) \(\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{21}{39}+\frac{49}{91}x\frac{8}{15}=\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{7}{13}+\frac{7}{13}x\frac{8}{15}\)
\(=\frac{7}{13}x\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{15}\right)=\frac{7}{13}x\left(1-\frac{5}{12}\right)=\frac{7}{13}x\frac{7}{12}=\frac{49}{156}\)
b) \(\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)=\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x0=0\)
Bài 2:
a) \(0,5+\left(x-\frac{15}{2}\right):\frac{1}{2}=\frac{9}{2}\)
\(\left(x-\frac{15}{2}\right):\frac{1}{2}=4\)
\(x-\frac{15}{2}=2\)
x = 19/2
b) \(2012\times x-2010\times x=2014\)
\(x\times\left(2012-2010\right)=2014\)
\(x\times2=2014\)
x = 1007
c) ( x + 1) + (x+2) + (x+3)+...+(x+100) = 5750
\(x\times100+\left(1+2+3+...+100\right)=5750\)
\(x\times100+5050=5750\)
\(x\times100=700\)
x = 7
( 15 - x ) + ( x - 12 ) = ( -5 + x )
( 15 - 12 ) - x + x = -5 + x
3 = -5 + x
x = 3 + 5
x = 8
(x+1)+(x+3)+(x+5)+...+(x+99)=0
( x + x + x + .... + x ) + ( 1 + 3 + 5 + ... + 99 ) = 0
50x + 2500 = 0
50x = -2500
x = -2500 : 50
x = -50
\(\dfrac{4}{6}-\dfrac{3}{5}=\dfrac{2}{3}-\dfrac{3}{5}=\dfrac{1}{15}\\ x=\dfrac{2}{3}-\dfrac{8}{21}=\dfrac{2}{7}\\ x=\dfrac{6}{7}\times\dfrac{1}{7}=\dfrac{6}{49}\\ 2-x=\dfrac{7}{9}\\ x=2-\dfrac{7}{9}=\dfrac{11}{9}\)
\(a,\dfrac{4}{6}-\left(\dfrac{6}{15}+\dfrac{1}{5}\right)=\dfrac{4}{6}-\dfrac{3}{5}=\dfrac{1}{15}\)
\(b,x=\dfrac{2}{3}-\dfrac{8}{21}\)
\(x=\dfrac{2}{7}\)
\(c,x=\dfrac{6}{7}\times\dfrac{1}{7}\)
\(x=\dfrac{6}{49}\)
\(d,2-x=\dfrac{7}{9}\)
\(x=2-\dfrac{7}{9}\)
\(x=\dfrac{11}{9}\)
1) 5.( x - 6 ) - 2.( x + 9 ) = 21
5x - 30 - 2x - 18 = 21
3x - 48 = 21
3x = 21 + 48
3x = 69
x = 23
2) 2.( x + 3 ) + 3.( x + 1 ) = 15 - ( - 9 )
2x + 6 + 3x + 3 = 24
5x + 9 = 24
5x = 24 - 9
5x = 15
x = 3
3) ( - x + 5 ).(3 - x ) = 0
=> - x + 5 = 0 hoặc 3 - x = 0
=> x = 5 hoặc x = 3
4) ( x - 12 ) - 15 = ( 20 - 7 ) - ( 18 + x )
x - 12 - 15 = 13 - 18 - x
x - 27 = - 5 - x
x + x = - 5 + 27
2x = 22
x = 11
5) x - ( 17 - 8 ) = 5 + ( 10 - 3x )
x - 9 = 5 + 10 - 3x
x + 3x = 15 + 9
4x = 24
x = 6
a) Ta có : ( x + 1 ).( 3 - x ) > 0
Th1 : \(\hept{\begin{cases}x+1>0\\3-x>0\end{cases}\Rightarrow\hept{\begin{cases}x>-1\\x>3\end{cases}\Rightarrow}x>3}\)
Th2 : \(\hept{\begin{cases}x+1< 0\\3-x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< -1\\x< 3\end{cases}\Rightarrow}x< -1}\)
a) 3*2x =48 \(\Leftrightarrow\)2x=16 \(\Leftrightarrow\)x=4 b) (2x +1 )3 =53 \(\Leftrightarrow\)2x +1 =5 \(\Leftrightarrow\)2x =4 \(\Leftrightarrow\)x=2 c) 36+x=36 \(\Leftrightarrow\)x=0 d) 1+x-15=27-1 \(\Leftrightarrow\)x=40