kazah
megoldása
1 éve
2,
a,
`x/2+x/9=44`
`(9x+2x)/18=44`
`(11x)/18=44`
`x/18=4`
x = 72
b,
`(x+1)/6-(x-1)/4=0`
`(2(x+1)-3(x-1))/12=0`
2x+2-3x+3=0
-x+5=0
x = 5
c,
`2x-(5/7*x-3/4*x)=57`
`2x-((20-21)x)/28`=57
`(57x)/28=57`
x = 28
d,
`6-(6x-4)/5=2x+(2-5x)/3`
`(90-(18x-12))/30=(30x+(10-25x))/30`
102-18x = 10+5x
23x = 92
x = 4
e,
`3x-(x+2)/4-(3x-2)/2=1-(x-1)/3`
`(36x-3x-6-18x+12)/12=(12-4x+4)/12`
15x+6 = 16-4x
19x = 10
x = `10/19`
f,
`x-(6-2x)/3=2x-4-(x+3)/2`
`(6x-12+4x)/6=(12x-24-3x-9)/6`
10x-12 = 9x-33
x = -21
g,
`x+(x+1)/4=2x+(5-3x)/2-(x-3)/8`
`(8x+2x+2)/8=(16x+20-12x-2x+6)/8`
10x+2 = 2x+26
8x = 24
x = 3
h,
`1-(6-2x)/3=x-(x+3)/2`
`(6-12+4x)/6=(6x-3x-9)/6`
4x-6 = 3x-9
x = -3
3,
a,
`x/(x-5)=5/(x-5)`
Felt: `x ne 5`
szorzunk a nevezővel.
x = 5
Mivel kizártuk, ezért nincs megoldás.
b,
`2/x+5/x=1`
Felt: `x ne 0`
`(2+5)/x` = 1
`7/x=1` /*x
x = 7
c,
`(x+3)/(4x)-1/2=(x-1)/(12x)+1/12`
Felt: `x ne 0`
`(3(x+3)-6x)/(12x)=((x-1)+x)/(12x)` (*12x)
3x+9-6x = 2x-1
-3x+9 = 2x-1
5x = 10
x = 2
d,
`(12x-9)/(3x-2)-(4x-5)/(2x-3)=2`
Felt: `x ne 2/3`, `x ne 3/2`
`(12x-9)*(2x-3)-(3x-2)*(4x-5)=2*(3x-2)*(2x-3)`
`24x^2-18x-36x+27-12x^2+8x+15x-10=2*(6x^2-4x-9x+6)`
`cancel(12x^2)-31x+17=cancel(12x^2)-26x+12`
5x = 5
x = 1
e,
`2x+(x^2-4)/(x+2)=1`
Felt: `x ne -2`
`2x+((x-2)*cancel(x+2))/(cancel(x+2))=1`
2x+x-2 = 1
3x = 3
x = 1
f,
`(9-x)/(x-4)=5/(x-4)+3`
Felt: `x ne 4`
`(9-x)/(x-4)=5/(x-4)+3*(x-4)`
9-x = 5+3x-12
4x = 16
x = 4; de a kezdeti feltétel miatt ez nem megoldás.
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