hỏi troll

Trả lời :

\(\frac{56^2}{28^2}=\frac{\left(2.28\right)^2}{28^2}=\frac{2^2.28^2}{28^2}=2^2=4\)

Study well 

hok tốt 

A; x=0 hoặc x=1

B; ....?

Trả lời

x:(1/2+1/3+1/6)=2019

x:6/6                =2019

     x:1              =2019

     =>x             =2019.1

     =>x             =2019

Học tốt !

x : (\(\frac{1}{2}\)+ \(\frac{1}{3}\)+ \(\frac{1}{6}\)) = 2019

x : 1 = 2019

x = 2019

#)Giải :

\(\frac{1}{15}+\frac{4}{30}+\frac{9}{45}+\frac{16}{60}+...+\frac{81}{135}=\frac{1}{15}+\frac{2}{15}+\frac{3}{15}+...+\frac{9}{15}=\frac{45}{15}=3\)

Dễ ẹc ak :v rút gọn là ra

=(\(\frac{1}{15}\)+\(\frac{4}{30}\)+\(\frac{16}{60}\)+\(\frac{64}{120}\))+(\(\frac{9}{45}\)+\(\frac{36}{90}\))+(\(\frac{25}{75}\)+\(\frac{81}{135}\))

=(\(\frac{8}{120}\)+\(\frac{16}{120}\)+\(\frac{32}{120}\)+\(\frac{64}{120}\))+(\(\frac{18}{90}\)+\(\frac{36}{90}\))+\(\frac{14}{15}\).

=1+\(\frac{3}{5}\)+\(\frac{14}{15}\).

=\(\frac{8}{5}\)+\(\frac{14}{15}\).

=\(\frac{15}{38}\)

Trả lời 

\(\left(2x+1\right)^2-2^2=117\)

\(\Rightarrow\left(2x+1\right)^2=121\)

\(\Rightarrow\left(2x+1\right)^2=11^2\)

\(\Rightarrow\orbr{\begin{cases}2x+1=11\\2x+1=-11\end{cases}}\orbr{\begin{cases}x=5\\x=-6\end{cases}}\)

Vậy x = 5 hoặc x = - 6

Study well 

(2x + 1)² - 2² = 117

<=> (2x + 1)² = 121

<=> (2x + 1)² = 11² = (-11)²

<=> \(\orbr{\begin{cases}2x+1=11\\2x+1=-11\end{cases}}\)

<=> \(\orbr{\begin{cases}x=5\\x=-6\end{cases}}\)

Vậy ... 

100-3(x-1)²=52

3(x-1)²=100-52

3(x-1)²=48

(x-1)²=48:3

(x-1)²=16

(x-1)²=4²=(-4)²

=> x-1=4 hoặc x-1=-4

TH1: 

x-1=4

x=4+1

x=5

TH2:

x-1=-4

x=-4+1

x=-3

Vậy x=5 hoặc x=-3

100 - 3(x - 1)² = 52

<=> 3(x - 1)² = 48

<=> (x - 1)² = 16

<=> (x - 1)² = 4² = (-4)²

<=> \(\orbr{\begin{cases}x-1=4\\x-1=-4\end{cases}}\)

<=> \(\orbr{\begin{cases}x=5\\x=-3\end{cases}}\)

\(35-3^{x+1}=8\)

\(\Rightarrow3^{x+1}=35-8=27\)

Mà \(27=3^3\)

\(\Rightarrow x+1=3\Rightarrow x=3-1=2\)

Vậy \(x=2\)

\(a.35-3^{x+1}=8\)

                \(3^x.3^1=35-8\)

                \(3^x.3^1=27\)

                \(3^x.3^1=3^3\)

                      \(3^x=3^3:3^1\)

                     \(3^x=3^{3-1}\)

                     \(3^x=3^2\)

                 \(\Rightarrow x=2\)

\(b.3.2^{x-1}+5=29\)

             \(3.2^x:2^1=29-5\)

             \(3.2^x:2^1=24\)

                  \(2^x:2^1=24:3\)

                  \(2^x:2^1=8\)

                  \(2^x:2^1=2^3\)

                        \(2^x=2^3.2^1\)

                        \(2^x=2^{3+1}\)

                        \(2^x=2^4\)

                    \(\Rightarrow x=4\)

\(c.9:3^x+15=18\)

  \(3^2:3^x+15=18-15\)

              \(3^2:3^x=3\)

                    \(3^x=3^2:3\)

                    \(3^x=3^{2-1}\)

                    \(3^x=3^1\)

                \(\Rightarrow x=1\)

Chúc bạn học tốt!