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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Tìm y ∈ Z: a) 7y – 4 = 20 + 3y b) 125 : (3y – 13) = 25 c) 5 x (y – 6) – 2 x (y + 3) = 12 d) 165 – 35 – (35 : y + 3) x 15 = 15 e

Tháng Ba 17, 2023 Toán học 1 Comment 0 views

Toán Lớp 6: Tìm y ∈ Z:
a) 7y – 4 = 20 + 3y
b) 125 : (3y – 13) = 25
c) 5 x (y – 6) – 2 x (y + 3) = 12
d) 165 – 35 – (35 : y + 3) x 15 = 15
e) (y – 1) x (y + 15) = -9

Comments ( 1 )

  1. truongthanhhung
    truongthanhhung
    17 Tháng Ba, 2023 at 6:45 sáng
    Reply
    $a)$
     $7y – 4 = 20 + 3y$
     $7y – 3y = 20 + 4$
           $4y = 24$
            $y = 6$
    $Vậy:$ $y = 6$
    $b)$
      $125:(3y – 13) = 25$
      $3y – 13 = 125 : 25$
        $3y – 13 = 5$
         $3y = 18$
           $y = 6$
    $Vậy:$ $y = 6$
    $c)$
    $5$ xx $(y – 6) – 2$ xx $(y + 3) = 12$
           $5y – 30 – 2y – 6 = 12$
               $3y – 36 = 12$
               $3y = 48$
                $y = 16$
    $Vậy:$ $y = 16$
    $d)$
    $165 – 35 – (35 : y + 3)$ xx $15 = 15$
    $(35 : y + 3)$ xx $15 = 165 – 35 – 15$
    $(35 : y + 3)$ xx $15 = 115$
     $35 : y + 3 = \frac{23}{3}$
           $35 : y = \frac{14}{3}$
           $y = \frac{15}{2}$ 
    $Vậy:$ $y = \frac{15}{2}$ 
    $e)$
    $(y – 1)$xx $(y + 15) = -9$
    $y(y + 15) – 1(y + 15) = -9$
    $y^2 + 15y – y – 15 = -9$
    $(y^2 – y) + (15y – 15) = -9$
    $y(y – 1) + 15(y – 1) = -9$
    $(y – 1)(y + 15) = -9$
    \(\left[ \begin{array}{l}y – 1 = -9\\y+15=-9\end{array} \right.\)
    \(\left[ \begin{array}{l}y=1\\y=-15\end{array} \right.\)
    $Vậy:$ $y = 1$ $hoặc$ $y=-15$
    Học tốt.
     

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222-9+11+12:2*14+14 = ? ( )

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