câu1 a 5. (x-7) = 7. (x-3) b3. (x-8)-6.(x-5)=12 c7.(x-4)-3.(x+8)=-84 d 6. (x-3)=8.(x-4) e 19-|2x+3|=-6 câu 2 3x+4y-xy=15

Question

câu1
a 5. (x-7) = 7. (x-3)
b3. (x-8)-6.(x-5)=12
c7.(x-4)-3.(x+8)=-84
d 6. (x-3)=8.(x-4)
e 19-|2x+3|=-6
câu 2
3x+4y-xy=15

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Eloise 2 tháng 2021-10-24T23:45:33+00:00 2 Answers 5 views 0

Answers ( )

    0
    2021-10-24T23:47:09+00:00

    $a, 5.(x-7)=7.(x-3)$

    $⇔5x-35=7x-21$

    $⇔5x-7x=-21+35$

    $⇔-2x=14$

    $⇔x=-7$

    $b,3.(x-8)-6.(x-5)=12$

    $⇔3x-24-6x+30=12$

    $⇔-3x=12+24-30$

    $⇔-3x=6$

    $⇔x=-2$

    $c,7.(x-4)-3.(x+8)=-84$

    $⇔7x-28-3x-24=-84$

    $⇔4x=-32$

    $⇔x=-8$

    $d,6.(x-3)=8.(x-4)$

    $⇔6x-18=8x-32$

    $⇔-2x=-14$

    $⇔x=7$

    $e,19-|2x+3|=-6$

    $⇔19-2x-3=-6$

    $⇔-2x=-22$

    $⇔x=11$

    0
    2021-10-24T23:47:14+00:00

    `\text{~~Holi~~}`

    `1.`

    `a. 5(x-7)=7(x-3)`

    `-> 5x-35=7x-21`

    `-> 5x-7x=-21+35`

    `-> -2x=14`

    `-> x=(14)/(-2)`

    `-> x=-7`

    Vậy `x=-7`

    `b. 3(x-8)-6(x-5)=12`

    `-> 3x-24-6x+30=12`

    `-> 3x-6x=12+24-30`

    `-> -3x=6`

    `-> x=6/(-3)`

    `-> x=-2`

    Vậy `x=-2`

    `c. 7(x-4)-3(x+8)=-84`

    `-> 7x-28-3x-24=-84`

    `-> 7x-3x=-84+28+24`

    `-> 4x=-32`

    `-> x=(-32)/4`

    `-> x=-8`

    Vậy `x=-8`

    `d. 6(x-3)=8(x-4)`

    `-> 6x-18=8x-32`

    `-> 6x-8x=-32+18`

    `-> -2x=-14`

    `-> 2x=14`

    `-> x=7`

    `e. 19-|2x+3|=-6`

    `-> |2x+3|=19-(-6)`

    `-> |2x+3|=25`

    `-> 2x+3=±25`

    `->`\(\left[ \begin{array}{l}2x+3=25\\2x+3=-25\end{array} \right.\) 

    `->`\(\left[ \begin{array}{l}x=11\\x=-14\end{array} \right.\) 

    Vậy `x\in{11;-14}`

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