`b)(x-22)/8 +(x-21)/9 + (x-20)/10 + (x-19)/11 = 4`
`<=>(x-22)/8 -1 +(x-21)/9 -1+ (x-20)/10 -1 + (x-19)/11 - 1 =0`
`<=>(x-22-8)/8+(x-21-9)/9+(x-20-10)/10+(x-19-11)/11=0`
`<=>(x-30)/8+(x-30)/9+(x-30)/10+(x-30)/11=0`
`<=>(x-30)(1/8+1/9+1/10+1/11)=0`
`<=>x-30=0`(vì `1/8+1/9+1/10+1/11≠0)`
`<=>x=30`
__________________________________
`d)(x+19)/3+(x+13)/5=(x+7)/7+(x+1)/9`
`<=>(x+19)/3+3+(x+13)/5+3=(x+7)/7+3+(x+1)/9+3`
`<=>(x+19+9)/3+(x+13+15)/5=(x+7+21)/7+(x+1+27)/9`
`<=>(x+28)/3+(x+28)/5=(x+28)/7+(x+1+27)/9`
`<=>(x+28)/3+(x+28)/5-(x+28)/7+(x+28)/9=0`
`<=>(x+28)(1/3+1/5-1/7-1/9)=0`
`<=>x+28=0` `(` Vì `1/3+1/5-1/7-1/9≠0)`
`<=>x=-28`
Đúng 1
Bình luận (0)