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a,12,5x(-5/7)+1,5x(-5/7)
=-125/14+-15/14
=-10
2,2mu800>8 mu 200
6254 lon hon 12
a) 52x+1=125
=>52x+1= 53
=>2x+1=3
=>2x = 2
=>x =1
c)73<x <=93
=>343<x<=729
=> x = { 344;345;...;729}
d) (2x+3)4=81
=>(2x+3)4=34
=>2x+3 =3
=>2x =0
=> x = 0
nhớ tk nha
a)52x+1=125
52x+1=53
⏩ 2x+1=3
2x=4
x=4:2
x=2
b) (2x)2(2x) 3 =25.25
(2x) 2 (2x) 3 =210
(2x) 5=1024
(2x) 5 =45
2x=4
x=4 :2=2
d)(2x +3)4=81
(2x +3)4=34
2x+3=3
2x=0
x=0
Câu c bạn tự giải nhé
Nhớ tk giùm mình đấy
Bài làm
m) (x + 2).(3 - x) = 0;
=> x + 2 = 0 hoặc 3 - x = 0
=> x = -2 hoặc x = 3
Vậy x = -2 hoặc x = 3
d) 511.712 + 511.711
= 511 . ( 712 + 711 )
= 511 . [ 711 . ( 7 + 1 ) ]
= 511 . 711 . 8
= ( 5 . 7 )11 . 8
= 3511 . 8
512.712 + 9.511.711
= 511 ( 5 . 712 + 9 . 1 . 711 )
= 511 [ 711 ( 5 . 7 + 9 . 1 . 1 ) ]
= 511 ( 711 . 44 )
= 511 . 711 . 44
= 3511 . 44
m. \(\left(x+2\right)\left(3-x\right)=0\Leftrightarrow\orbr{\begin{cases}x+2=0\\3-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=3\end{cases}}\)
d. \(\frac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}=\frac{5^{11}.\left(7^{12}+7^{11}\right)}{5^{11}.\left(5.7^{12}+9.7^{11}\right)}=\frac{7^{12}+7^{11}}{5.7^{12}+9.7^{11}}=\frac{1}{5.9}=\frac{1}{45}\)
q. \(\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+...+10+11=11\)
\(\Rightarrow\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+...+10=0\)
\(\Rightarrow\left[\left(x-3\right)+\left(x-2\right)+\left(x-1\right)\right]+(1+2+3+...+10)=0\)
\(\Rightarrow\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+55=0\)
\(\Rightarrow x-3+x-2+x-1=-55\)
\(\Rightarrow3x-6=-55\)
\(\Rightarrow3x=-49\)
\(\Rightarrow x=-\frac{49}{3}\)
Bài 1:
a)A=1+3+33+34+...+32018
3A=3+32+34+35+...+32019
3A-A=(3+32+34+35+...+32019)-(1+3+33+34+...+32018)
2A=32019-1
A=(32019-1):2
Bài 2:
a)(4x+5):3-121:11=4
(4x+5):3-11=4
(4x+5):3=4+11
(4x+5):3=15
4x+5=15:3
4x+5=5
4x=5-5
4x=0
x=0:4
x=0
Bài 3:
813.1255=(34)3.(53)5=312.515=(3.5)12.53=1512.53
Ta có:1512<1512.53
Vậy 1512<813.1255.
Bài 1:
a)12,5 x (-5/7) + 1,5 x (-5/7)
=-5/7*(12,5+1,5)
=-5/7*14
=-10
b)(-1/4) x (6|2/11) + 3|9/11 x (-1/4)
=-1/4*(68/11+42/11)
=-1/4*10
=-5/2
c tương tự
d)\(\frac{9^8\cdot4^3}{27^4\cdot6^5}=\frac{\left(3^2\right)^8\cdot\left(2^2\right)^3}{\left(3^3\right)^4\cdot\left(2\cdot3\right)^5}=\frac{3^{16}\cdot2^6}{3^{12}\cdot2^5\cdot3^5}=\frac{3^{16}\cdot2^5\cdot2}{3^{16}\cdot3^1\cdot2^5}=\frac{2}{3}\)
Bài 2:
a)Ta có:
2800=(28)100=256100
8200=(82)100=64100
Vì 256100>64100 =>2800>8200
b)Ta có:
1245=(123)15=172815
Vì 62515<172815 =>62515<1245
a) -5/7x(12,5+1,5)=-10
b) -1/4x (6I2/11+3I9/11) = -1/4x 10=-5/2
c) (-7/5 + -3/8 + -3/5+5/8): 2009/2010 = -7/4:2009/2010=-1005/574
d)3^16x 4^3/3^12x 6^5=3^4x4^3x6^5=......
bài 2)
2^800=2^4x200= 15^200> 8^200
=> 2^800>8^200
B) quên cách làm