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

Toán Lớp 6: Bài 1: tìm x biết a) 17 – 3mũ x = -10 b) -2x – 40 (5-x)- (-15)+60) c) -6x + 93 = -3 d) 5x – 7 =2x + 8

Toán Lớp 6: Bài 1: tìm x biết
a) 17 – 3mũ x = -10
b) -2x – 40 (5-x)- (-15)+60)
c) -6x + 93 = -3
d) 5x – 7 =2x + 8

Comments ( 2 )

  1. a)17 – 3^x=-10
    3^x=17-(-10)
    3^x=17+10
    3^x=27
    3^x=3^3
    ⇒x=3
    Vậy: x=3
    b) -2x – 40 (5-x)- (-15)+60
    =-2x – 40 (5-x)+15+60
    =-2x – 40 .5-40x+75
    =-2x -200-40x+75
    =-2x-40x-200+75
    =(-2-40).x-125
    =-42x-125
    c) -6x + 93 = -3
    -6x=-3-93
    -6x=-96
    x=-96:(-6)
    x=16
    Vậy x=16
    d) 5x – 7 =2x + 8
    5x-2x=8+7
    3x=15
    x=15:3
    x=5
    Vậy x=5

  2. a) 17-3^x=-10
    ⇔3^x=17-(-10)
    ⇔3^x=27
    ⇔3^x=3^3
    ⇔x=3
    Vậy x=3
    b) -2x-40=(5-x)-(-15)+60
    ⇔-2x-40=5-x+15+60
    ⇔-2x-40=5-x+75
    ⇔-2x+x=5+75+40
    ⇔-x=120
    ⇔x=-120
    Vậy x=-120
    c) -6x+93=-3
    ⇔-6x=-3-93
    ⇔-6x=-96
    ⇔x=(-96) :(-6)
    ⇔x=16
    Vậy x=16
    d) 5x-7=2x+8
    ⇔5x-2x=8+7
    ⇔3x=15
    ⇔x=5
    Vậy x=5
     

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