bài 1: a) 45 mũ 3.20 mũ 4.18 mũ 2 phần 180 mũ 5 b)2 mũ 13+2 mũ 5 phần 2 mũ 10 + 2 mũ 2 bài 2:tìm x a) 50-5.(x-3)=30 b) 14+5mũ 2.x=4 mũ 6:4mũ 3 c)x ch

0 bình luận về “bài 1: a) 45 mũ 3.20 mũ 4.18 mũ 2 phần 180 mũ 5 b)2 mũ 13+2 mũ 5 phần 2 mũ 10 + 2 mũ 2 bài 2:tìm x a) 50-5.(x-3)=30 b) 14+5mũ 2.x=4 mũ 6:4mũ 3 c)x ch”

1. Đáp án:

   $\begin{array}{l}
   1)a)\dfrac{{{{45}^3}{{.20}^4}{{.18}^2}}}{{{{180}^5}}}\\
    = \dfrac{{{{\left( {{3^2}.5} \right)}^3}.{{\left( {{2^2}.5} \right)}^4}.{{\left( {{{2.3}^2}} \right)}^2}}}{{{{\left( {{2^2}{{.3}^2}.5} \right)}^5}}}\\
    = \dfrac{{{3^6}{{.5}^3}{{.2}^8}{{.5}^4}{{.2}^2}{{.3}^4}}}{{{2^{10}}{{.3}^{10}}{{.5}^5}}}\\
    = {5^2} = 25\\
   b)\dfrac{{{2^{13}} + {2^5}}}{{{2^{10}} + {2^2}}} = \dfrac{{{2^5}\left( {{2^8} + 1} \right)}}{{{2^2}\left( {{2^8} + 1} \right)}} = {2^3} = 8\\
   B2)a)50 – 5\left( {x – 3} \right) = 30\\
    \Rightarrow 5\left( {x – 3} \right) = 50 – 30\\
    \Rightarrow 5\left( {x – 3} \right) = 20\\
    \Rightarrow x – 3 = 4\\
    \Rightarrow x = 7\\
   Vậy\,x = 7\\
   b)14 + {5^2}.x = {4^6}:{4^3}\\
    \Rightarrow 14 + 25.x = {4^3}\\
    \Rightarrow 14 + 25.x = 64\\
    \Rightarrow 25.x = 50\\
    \Rightarrow x = 2\\
   Vậy\,x = 2\\
   c)x \vdots 12;x \vdots 25;x \vdots 30\left( {500 < x < 700} \right)\\
    \Rightarrow x = BC\left( {12;25;30} \right)\\
   Do:12 = {2^2}.3;25 = {5^2};30 = 2.3.5\\
    \Rightarrow BCNN\left( {12;25;30} \right) = {2^2}{.3.5^2} = 300\\
    \Rightarrow x \in \left\{ {300;600;900;…} \right\}\\
    \Rightarrow x = 600\left( {do:500 < x < 700} \right)\\
   Vậy\,x = 600\\
   d)\left( {x + 4} \right) \vdots \left( {x + 1} \right)\\
    \Rightarrow \left( {x + 1 + 3} \right) \vdots \left( {x + 1} \right)\\
    \Rightarrow 3 \vdots \left( {x + 1} \right)\\
    \Rightarrow \left( {x + 1} \right) \in \left\{ { – 3; – 1;1;3} \right\}\\
    \Rightarrow x \in \left\{ { – 4; – 2;0;2} \right\}
   \end{array}$

   Trả lời