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Bài 1:
a) 23=2.2.2=823=2.2.2=8;
24=23.2=8.2=1624=23.2=8.2=16;
25=24.2=16.2=3225=24.2=16.2=32;
26=25.2=32.2=6426=25.2=32.2=64;
27=26.2=64.2=12827=26.2=64.2=128;
28=27.2=128.2=25628=27.2=128.2=256;
29=28.2=256.2=51229=28.2=256.2=512;
210=29.2=512.2=1024210=29.2=512.2=1024
b) 32=3.3=932=3.3=9;
33=32.3=9.3=2733=32.3=9.3=27;
34=33.3=27.3=8134=33.3=27.3=81;
35=34.3=81.3=24335=34.3=81.3=243.
c) 42=4.4=1642=4.4=16;
43=42.4=16.4=6443=42.4=16.4=64;
44=43.4=64.4=25644=43.4=64.4=256.
d) 52=5.5=2552=5.5=25;
53=52.5=25.5=12553=52.5=25.5=125;
54=53.5=125.5=62554=53.5=125.5=625.
e) 62=6.6=3662=6.6=36;
63=62.6=36.6=21663=62.6=36.6=216;
64=63.6=216.6=129664=63.6=216.6=1296.
a) \(6x-39=6528:28\)
\(6x-39=\frac{1632}{7}\)
\(6x=\frac{1632}{7}+39\)
\(6x=\frac{1905}{7}\)
\(x=\frac{1905}{7}:6\)
\(x=\frac{635}{14}\)
b) \(2^{x+1}+54=86\)
\(2^{x+1}=32\)
\(2x.2^2=32\)
\(2x=8\)
\(x=4\)
c) \(\left|x-18\right|.2^{2018}=2^{2020}\)
\(\left|x-18\right|=2^{2020}:2^{2018}\)
\(\left|x-18\right|=2^{2020-2018}=2^2=4\)
\(\Rightarrow\orbr{\begin{cases}x-18=4\\x-18=-4\end{cases}\Rightarrow\orbr{\begin{cases}x=22\\x=14\end{cases}}}\)
d) \(6x-36=2^3.3^2\)
\(6x-36=72\)
\(6x=108\)
\(x=18\)
e) \(\left|x-5\right|=8\)
\(\Rightarrow\orbr{\begin{cases}x-5=8\\x-5=-8\end{cases}\Rightarrow\orbr{\begin{cases}x=13\\x=-3\end{cases}}}\)
hok tốt!!
Mik làm được 1 bài thôi . Tiếc quá mình sắp phải đi học rồi.
BÀi 12:
S=1 + 2 + 22 + `23 +..........+ 22017
2S=2 + 22 + `23 + 24 +..........+22017 + 22018
Trừ đi hai vế ta được:
S=1 + 22018
A=2020^10+2/2020^11+2
⇒ 2020A=2020^11+2.2020/2020^11+2
= 1+2.2020−2/2020^11+2
B=2020^11+2/2020^12+2
⇒ 2020B=2020^12+2.2020/2020^12+2
= 1+2.2020−2/2020^12+2
Vì 2020^12+2>2020^11+2
⇒ 2.2020−2/2020^11+2<2.2020−2/2020^12+2
⇒ 2020A<2020B
⇒ A<B
\(P=1-2^2+3^2-4^2+...+99^2-100^2\)
\(=\left(1-2\right)\left(1+2\right)+\left(3-4\right)\left(3+4\right)+...+\left(99-100\right)\left(99+100\right)\)
\(=-\left(3+7+...+199\right)\)
P có số phần tử \(\frac{199-3}{4}+1=50\)
\(-P=\frac{50\left(199+3\right)}{2}=5050\)
\(\Rightarrow P=-5050\)
Đặt A=12-22+.....-20162
=> -A=22-12+42-32+62-52...+20162-20152
-A=(2-1)(2+1)+(4-3)(4+3)+(6-5)(6+5)...+(2016-2015)(2016+2015)
-A=3+7+11+...+4031
-A=[(4031-3):4+1]:2 x (3+4031)
-A=2033136
A=-2033136
\(-3^2+\left\{-54:\left[\left(-2\right)^3+7.|-2|\right]\right\}.\left(-2\right)^2\)'
=\(9+\left\{-54:\left[\left(-8\right)+7.2\right]\right\}.4\)
\(=9+\left\{-54:\left[\left(-8\right)+14\right]\right\}.4\)
\(=9+\left\{-54:6\right\}.4\)
\(=9+\left(-9\right).4\)
\(=9+\left(-36\right)\)
\(=-27\)
chúc bạn học tốt