0
0
Hãy luôn nhớ cảm ơn và vote 5*
nếu câu trả lời hữu ích nhé!
`a.`
`6+2.(x-2)=3(4-3x)+1`
`<=>6+2x-4=12-9x+1`
`<=>2x+9x=12+1-6+4`
`<=>11x=11`
`<=>x=1`
Vậy `S={1}`
`b.`
`(x^2-4)(x^2-5x+7)=(x^2-4)(2x^2+3x-13)`
`<=>(x^2-4)(x^2-5x+7)-(x^2-4)(2x^2+3x-13)=0`
`<=>(x^2-4)(x^2-5x+7-2x^2-3x+13)=0`
`<=>(x-2)(x+2)(-x^2-8x+20)=0`
`<=>(x-2)(x+2)(x^2+8x-20)=0`
`<=>(x-2)(x+2)(x^2+10x-2x-20)=0`
`<=>(x-2)(x+2)[x(x+10)-2(x+10)]=0`
`<=>(x-2)(x+2)(x-2)(x+10)=0`
`<=>(x-2)(x+2)(x+10)=0`
`<=>` \(\left[ \begin{array}{l}x-2=0\\x+2=0\\x+10=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2\\x=-2\\x=-10\end{array} \right.\)
Vậy `S={2;-2;-10}`
`c.`
`(11x+2)/4-(4x-1)/9=(13x+2)/12-2`
`<=> (11x+2)/4-(4x-1)/9-(13x+2)/12+2=0`
`<=>(9(11x+2))/36-(4(4x-1))/36-(3(13x+2))/36+72/36=0`
`<=>(9(11x+2)-4(4x-1)-3(13x+2)+72)/36=0`
`<=> 9(11x+2)-4(4x-1)-3(13x+2)+72==0`
`<=>99x+18-16x+4-39x-6+72=0`
`<=>44x+88=0`
`<=>44x=-88`
`<=>x=-2`
Vậy `S={-2}`
`d.`
`(x+1)/9-(x-1)/6=2-(x+3)/2`
`<=> (x+1)/9-(x-1)/6-2+(x+3)/2=0`
`<=> (6(x+1))/54-(9(x-1))/54-108/54+(27(x+3))/54=0`
`<=>(6(x+1)-9(x-1)-108+27(x+3))/54=0`
`<=> 6(x+1)-9(x-1)-108+27(x+3)=0`
`<=>6x+6-9x+9-108+27x+81=0`
`<=>24x-12=0`
`<=>24x=12`
`<=>x=12/24`
`<=>x=1/2`
Vậy `S={1/2}`
`e.`
`(x+29)/31-(x+27)/33=(x+17)/43-(x+15)/45`
`<=> (x+29)/31-(x+27)/33-(x+17)/43+(x+15)/45=0`
`<=> ((x+29)/31+1) -((x+27)/33+1)-((x+17)/43+1)+((x+15)/45+1)=0`
`<=>((x+29)/31+31/31) -((x+27)/33+33/33)-((x+17)/43+43/43)+((x+15)/45+45/45)=0`
`<=>(x+60)/31-(x+60)/33-(x+60)/43+(x+60)/45=0`
`<=>(x+60)(1/31-1/33-1/43+1/45)=0`
Vì `1/31-1/33-1/43+1/45 !=0`
`<=>x+60=0`
`<=>x=-60`
Vậy `S={-60}`
Hãy giúp mọi người biết câu trả lời này thế nào?
Đáp án + Giải thích các bước giải:
a)
`6+2(x-2)=3(4-3x)+1`
`<=>6+2x-4=12-9x+1`
`<=>2x+9x=12+1+4-6`
`<=>11x=11`
`<=>x=1`
Vậy `S={1}`
b)
`(x^2-4)(x^2-5x+7)=(x^2-4)(2x^2+3x-13)`
`<=>(x-2)(x+2)(x^2-5x+7)-(x-2)(x+2)(2x^2+3x-13)=0`
`<=>(x-2)(x+2)(x^2-5x+7-2x^2-3x+13)=0`
`<=>(x-2)(x+2)(-x^2-8x+20)=0`
`<=>(x-2)(x+2)(x^2+10x-2x-20)=0`
`<=>(x-2)(x+2)[x(x+10)-2(x+10)]=0`
`<=>(x-2)^2 (x+2)(x+10)=0`
`<=>[((x-2)^2=0),(x+2=0),(x+10=0):}`
`<=>[(x=2),(x=-2),(x=-10):}`
Vậy `S={2;-2;-10}`
c)
`(11x+2)/4-(4x-1)/9=(13x+2)/12-2`
`<=>(11x+2)/4-(4x-1)/9-(13x+2)/12+2=0`
`<=>(9(11x+2))/36-(4(4x-1))/36-(3(13x+2))/36+72/36=0`
`<=>(99x+18-16x+4-39x-6+72)/36=0`
`<=>44x+88=0`
`<=>x=-2`
Vậy `S={-2}`
d)
`(x+1)/9-(x-1)/6=2-(x+3)/2`
`<=>(x+1)/9-(x-1)/6+(x+3)/2-2=0`
`<=> (6(x+1))/54-(9(x-1))/54-108/54+(27(x+3))/54=0`
`<=>(6x+6-9x+9-108+27x+81)/54=0`
`<=>24x-12=0`
`<=>x=1/2`
Vậy `S={1/2}`
e)
`(x+29)/31-(x+27)/33=(x+17)/43-(x+15)/45`
`<=>(x+29)/31+1-(x+27)/33-1=(x+17)/43+1-(x+15)/45-1`
`<=>(x+29+31)/31-(x+27+33)/33=(x+17+43)/43-(x+15+45)/45`
`<=>(x+60)/31-(x+60)/33-(x+60)/43+(x+60)/45=0`
`<=>(x+60).(1/31-1/33-1/43+1/45)=0`
Mà: `1/31-1/33-1/43+1/45\ne0`
`<=>x+60=0`
`<=>x=-60`
Vậy `S={-60}`
Hãy giúp mọi người biết câu trả lời này thế nào?
Bảng tin
2117
14797
1790
uy tín k đấy
2117
14797
1790
éc =)
2016
19118
1460
:V ...
2016
19118
1460
chửi v cày lên `700` chs
2117
14797
1790
th xin =))
2016
19118
1460
đùa đấy, tý nx ko cướp top 1 aau,
0
47
0
qua giúp tui bài 2 đc ko zợ
2117
14797
1790
ummm