Toán Lớp 7: a/ 112 -3x = 4x + 49
b/ (2x – 8) (15 -3x) = 0
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Toán Lớp 7: a/ 112 -3x = 4x + 49
b/ (2x – 8) (15 -3x) = 0
Comments ( 2 )
112-3x=4x+49
=>-3x-4x=49-112
=>x.(-3-4)=-63
=>-7x=-63
=>x=(-63):(-7)
=>x=9
Vậy x=9
b)
(2x-8)(15-3x)=0
=>[(2x-8=0),(15-3x=0):}
=>[(2x=0+8),(3x=0+15):}
=>[(2x=8),(3x=15):}
=>[(x=8:2),(x=15:3):}
=>[(x=4),(x=5):}
Vậy x\in{4;5}