(-3)^(x-5)=-1/27 (-5)^(x+3)=-1/125 2*3^(x+2)+4*3^(x+1)=10*3^6 6*8^(x-1)+8^(x+1)=6*8^19+8^21

Question

(-3)^(x-5)=-1/27
(-5)^(x+3)=-1/125
2*3^(x+2)+4*3^(x+1)=10*3^6
6*8^(x-1)+8^(x+1)=6*8^19+8^21

in progress 0
Nick 1 year 2020-11-27T06:24:42+00:00 1 Answers 43 views 0

Answers ( )

    0
    2020-11-27T06:26:31+00:00

    Đáp án:

    $\begin{array}{l}
    a){\left( { – 3} \right)^{x – 5}} =  – \dfrac{1}{{27}}\\
     \Rightarrow {\left( { – 3} \right)^{x – 5}} = \dfrac{1}{{{{\left( { – 3} \right)}^3}}}\\
     \Rightarrow {\left( { – 3} \right)^{x – 5}} = {\left( { – 3} \right)^{ – 3}}\\
     \Rightarrow x – 5 =  – 3\\
     \Rightarrow x =  – 3 + 5 = 2\\
    Vay\,x = 2\\
    b){\left( { – 5} \right)^{x + 3}} =  – \dfrac{1}{{125}}\\
     \Rightarrow {\left( { – 5} \right)^{x + 3}} = {\left( { – 5} \right)^{ – 3}}\\
     \Rightarrow x + 3 =  – 3\\
     \Rightarrow x =  – 6\\
    Vay\,x =  – 6\\
    c){2.3^{x + 2}} + {4.3^{x + 1}} = {10.3^6}\\
     \Rightarrow {2.3^{x + 1}}.3 + {4.3^{x + 1}} = {10.3^6}\\
     \Rightarrow {3^{x + 1}}.\left( {6 + 4} \right) = {10.3^6}\\
     \Rightarrow {3^{x + 1}}.10 = {10.3^6}\\
     \Rightarrow {3^{x + 1}} = {3^6}\\
     \Rightarrow x + 1 = 6\\
     \Rightarrow x = 5\\
    Vay\,x = 5\\
    d){6.8^{x – 1}} + {8^{x + 1}} = {6.8^{19}} + {8^{21}}\\
     \Rightarrow {6.8^{x – 1}} + {8^{x – 1 + 2}} = {6.8^{19}} + {8^{19 + 2}}\\
     \Rightarrow {8^{x – 1}}\left( {6 + {8^2}} \right) = {8^{19}}.\left( {6 + {8^2}} \right)\\
     \Rightarrow {8^{x – 1}} = {8^{19}}\\
     \Rightarrow x – 1 = 19\\
     \Rightarrow x = 20\\
    Vay\,x = 20
    \end{array}$

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )