a,2.(x-1)-86=14 b, 9.x-13=671 c, 31.(x-405).67=0 d, 3.(x+7)-21=51 e, 4.(x+5)+44=100

Bởi

a,2.(x-1)-86=14
b, 9.x-13=671
c, 31.(x-405).67=0
d, 3.(x+7)-21=51
e, 4.(x+5)+44=100

0 bình luận về “a,2.(x-1)-86=14 b, 9.x-13=671 c, 31.(x-405).67=0 d, 3.(x+7)-21=51 e, 4.(x+5)+44=100”

  1. Đáp án:

    \(\eqalign{
    & a)\,x = 51 \cr
    & b)\,\,x = 76 \cr
    & c)\,\,x = 405 \cr
    & d)\,\,x = 17 \cr
    & e)\,\,x = 9 \cr} \)

    Giải thích các bước giải:

    \(\eqalign{
    & a)\,\,2\left( {x – 1} \right) – 86 = 14 \cr
    & \Leftrightarrow 2\left( {x – 1} \right) = 14 + 86 \cr
    & \Leftrightarrow 2\left( {x – 1} \right) = 100 \cr
    & \Leftrightarrow x – 1 = 50 \cr
    & \Leftrightarrow x = 51 \cr
    & b)\,\,9x – 13 = 671 \cr
    & \Leftrightarrow 9x = 671 + 13 \cr
    & \Leftrightarrow 9x = 684 \cr
    & \Leftrightarrow x = 76 \cr
    & c)\,\,31\left( {x – 405} \right).67 = 0 \cr
    & \Leftrightarrow x – 405 = 0 \cr
    & \Leftrightarrow x = 405 \cr
    & d)\,\,3\left( {x + 7} \right) – 21 = 51 \cr
    & \Leftrightarrow 3\left( {x + 7} \right) = 51 + 21 \cr
    & \Leftrightarrow 3\left( {x + 7} \right) = 72 \cr
    & \Leftrightarrow x + 7 = 24 \cr
    & \Leftrightarrow x = 17 \cr
    & e)\,\,4\left( {x + 5} \right) + 44 = 100 \cr
    & \Leftrightarrow 4\left( {x + 5} \right) = 100 – 44 \cr
    & \Leftrightarrow 4\left( {x + 5} \right) = 56 \cr
    & \Leftrightarrow x + 5 = 14 \cr
    & \Leftrightarrow x = 9 \cr} \)

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