Toán Lớp 6: 7) 440 + 2. (125 – x) = 546 8) 846 : [41 – (7x – 5)] = 47 9) (4x – 1)2 = 25. 9

Question

Toán Lớp 6:  7) 440 + 2. (125 – x) = 546  8) 846 : [41 – (7x – 5)] = 47  9) (4x – 1)2 = 25. 9

cattien · Answer

$ #phnn$ 7)440+2.(126-x)=546 <=>2.(126-x)=546-440 <=>2.(126-x)=106 <=>126-x=106:2 <=>126-x=53 <=>-x=53-126 <=>-x=-73 <=>x=73 text{Vậy} x=73. 8)846:[41-(7x-5)]=47 <=>41-(7x-5)=846:47 <=>41-(7x-5)=18 <=>7x-5=41-18 <=>7x-5=23 <=>7x=23+5 <=>7x=28 <=>x=28:7 <=>x=4 text{Vậy} x=4. 9)(4x-1)^2=25.9 <=>(4x-1)^2=225 <=>(4x-1)^2=(±15)^2 text{Trường hợp 1:} 4x-1=15 <=>4x=15+1 <=>4x=16 <=>x=16:4 <=>x=4 text{Trường hợp 2:} 4x-1=-15 <=>4x=-15+1 <=>4x=-14 <=>x=-14:4 <=>x=-7/2 text{Vậy} x=4 text{hoặc} x=-7/2.

truongthanhhung · Answer

7 ) 440 + 2.(125 - x) = 546   2.(125 - x) = 546 - 440   2.(125 - x) = 106   125 - x = 106 : 2   125 - x = 53            x = 125 - 53             x = 72   Vậy x = 72   8 ) 846 : [41 - (7x -5)] = 47   41 - (7x -5) = 846 : 47   41 - (7x - 5) = 18   7x - 5 = 41 - 18   7x - 5 = 23   7x = 23 + 5   7x = 28     x = 28 : 7      x = 4   Vậy x = 4   9 ) (4x - 1)^2 = 25 . 9   (4x - 1)^2 = 225   (4x - 1)^2 = 15^2   => 4x - 1 = 15   4x = 15 + 1   4x = 16      x = 16 : 4       x = 4   Vậy x = 4    #dtkc