a: =>3x=9
hay x=3
b: =>x-42=17
hay x=59
c: =>8x-16=0 hoặc x-5=0
=>x=2 hoặc x=5
e: =>2x=12
hay x=6
g: =>3x=15
hay x=5
a.
<=> x.3 = 16 - 17 = 9
=> x = 9 : 3 = 3
b.
<=> x - 42 = 51 : 3 = 17
=> x = 17 + 42 = 59
c.
<=>
8x - 16 = 0
x - 5 = 0
<=>
8x = 16
x = 0 + 5
<=>
x = 16 : 8 = 2
x = 5
d.
<=> x - 76 = 46
=> x = 46 + 76 = 122
e.
<=> 2.x = 15 - 3
<=> 2.x = 12
=> x = 12:2 = 6
g.
<=> 3x = 28 - 13 = 15
=> x = 15 : 3 =5
h.
<=> x - 1954 = 50 : 5 = 10
=> x = 10 + 1954 = 1964
i.
<=> 60 - x = 30 : 30 = 1
=> x = 60 - 1 = 59
k.
<=> x + 33 = 55
=> x =55 -33 = 22
m.
<=> x - 25 = 20 x 15 = 300
=> x = 300 + 25 = 325
n.
<=> 3x - 15 = 42 : 7 = 6
<=> 3x = 6 + 15 = 21
=> x = 21 : 3 = 7
`a, x.3 + 7 = 16`
`3x=16-7`
`3x=9`
`x=9:3`
`x=3`
____________________________
`b, (x - 42).3 = 51`
`x-42=51:3`
`x-42=17`
`x=17+42`
`x=59`
_________________________
`c, (8x - 16) (x - 5) = 0`
`@Th1:`
`8x-16=0`
`8x=16`
`x=16:8`
`x=2`
`@TH2:`
`x-5=0`
`x=0+5`
`x=5`
________________________________
`d, x - 152 : 2 = 46`
`x-76=46`
`x=46+76`
`x=122`
___________________________
`e, 2.x + 3 = 15`
`2x=15-3`
`2x=12`
`x=12:2`
`x=6`
______________________________
`g, 28 - 3 .x = 13`
`3x=28-13`
`3x=15`
`x=15:3`
`x=5`
____________________________
`h, (x - 1954) .5 = 50`
`x-1954=50:5`
`x-1954=10`
`x=10+1954`
`x=1964`
______________________________
`i, 30.(60 - x) = 30`
`60-x=30:30`
`60-x=1`
`x=60-1`
`x=59`
_______________________________
`k, x + 99 : 3 = 55`
`x+33=55`
`x=55-33`
`x=22`
_______________________________
`m, (x - 25) : 15 = 20`
`x-25=20xx15`
`x-25=300`
`x=300+25`
`x=325`
__________________________________
`n, (3.x - 15).7 = 42`
`3x-15=42:7`
`3x-15=6`
`3x=6+15`
`3x=21`
`x=21:3`
`x=7`
________________________________
`l, x.(x + 1) = 2 + 4 + 6 + 8 + 10 + ... + 2500`
`2+4+6+8+.....+2500`
Số hạng :
`(2500-2)/2 + 1 = 1250`
Tổng:
`(2500+2)xx1250:2=1563750`
`=> x.(x + 1) = 1563750`
`=> x=1250`
hoặc `x = -1251`
