0
0
Hãy luôn nhớ cảm ơn và vote 5*
nếu câu trả lời hữu ích nhé!
6659
6741
`7)A=((sqrt7-sqrt21)/(1-sqrt3)-(sqrt2-sqrt10)/(1-sqrt5)): 1/(sqrt2+sqrt7)`
`=((sqrt7(1-sqrt3))/(1-sqrt3))-(sqrt2(1-sqrt5))/(1-sqrt5))(sqrt2+sqrt7)`
`=(sqrt7-sqrt2)(sqrt7+sqrt2)`
`=7-2`
`=5`
`8)ĐK:{(sqrtx>=0),(x-1 ne0),(sqrtx ne0):}`
`<=>{(x>=0),(x ne1),(x ne0):}`
`<=>{(x>0),(x ne1):}`
`P=(sqrtx/(sqrtx-1)-1/(x-sqrtx)):(1/(sqrtx+1)+2/(x-1))`
`=(sqrtx/(sqrtx-1)-1/(sqrtx(sqrtx-1))):(1/(sqrtx+1)+2/((sqrtx-1)(sqrtx+1)))`
`=(sqrtx.sqrtx-1)/(sqrtx(sqrtx-1)): (sqrtx-1+2)/((sqrtx+1)(sqrtx-1))`
`=((sqrtx-1)(sqrtx+1))/(sqrtx(sqrtx-1)) :(sqrtx+1)/((sqrtx+1)(sqrtx-1))`
`=(sqrtx-1)/sqrtx . (sqrtx-1)`
`=(sqrtx-1)^2/sqrtx`
Hãy giúp mọi người biết câu trả lời này thế nào?
Bảng tin