Đáp án:
Bài cuối nhìn rối quá nhỉ @-@
Giải thích các bước giải:
`a)` Điều kiện:`{(a>=0),(b>=0),(ab>0),(sqrta-sqrtb ne 0):}`
`<=>{(a>0),(b>0),(a ne b):}`
`b)M=((sqrta+sqrtb)^2-4sqrt{ab})/(sqrt{a}-sqrtb)-(asqrtb+bsqrta)/sqrt{ab}`
`M=(a+2sqrt{ab}+b-4sqrt{ab})/(sqrta-sqrtb)-(sqrt{ab}(sqrta-sqrtb))/sqrt{ab}`
`M=(a-2sqrt{ab}+b)/(sqrta-sqrtb)-(sqrta-sqrtb)`
`M=(sqrta-sqrtb)^2/(sqrta-sqrtb)-(sqrta-sqrtb)`
`M=(sqrta-sqrtb)-(sqrta-sqrtb)`
`M=0` không phụ thuộc vào m
`6)N=((2x+1)/(sqrt{x^3}-1)-sqrtx/(x+sqrtx+1))((1+sqrt{x^3})/(1+sqrtx)-sqrtx)`
`N=((2x+1)/((sqrtx-1)(x+sqrtx+1))-(sqrtx(sqrtx-1))/((sqrtx-1)(x+sqrtx+1)))*(((sqrtx+1)(x-sqrtx+1))/(1+sqrtx)-sqrtx)`
`N=((2x+1-x+sqrtx)/((sqrtx+1)(x+sqrtx+1)))*(x-sqrtx+1-sqrtx)`
`N=((x+sqrtx+1)/((sqrtx-1)(x+sqrtx+1)))*(x-2sqrtx+1)`
`N=(1/(sqrtx-1))*(sqrtx-1)^2`
`N=sqrtx-1`
`b)N=3`
`<=>sqrtx-1=3`
`<=>sqrtx=4`
`<=>x=16(tmđk)`
`7)R=(sqrtx/(3+sqrtx)-(x+9)/(9-x)):((3sqrtx+1)/(x-3sqrtx)-1/sqrtx)(x>0,x ne 9)`
`a)R=((sqrtx(sqrtx-3))/((sqrtx-3)(sqrtx+3))+(x+9)/((sqrtx-3)(sqrtx+3))):((3sqrtx+1)/(sqrtx(sqrtx-3))-(sqrtx-3)/(sqrtx(sqrtx-3)))`
`R=((x-3sqrtx+x+9)/((sqrtx-3)(sqrtx+3))):((2sqrtx+4)/(sqrtx(sqrtx-3))`
`R=(2x-3sqrtx+9)/((sqrtx-3)(sqrtx+3))*(sqrtx(sqrtx-3))/(2sqrtx+4)`
`R=(sqrtx(2x-3sqrtx+9))/((2sqrtx+4)(sqrtx+3))`
`R=(2xsqrtx-3x+9sqrtx)/(2x+10sqrtx+12)`
`b)R=3`
`<=>2xsqrtx-3x+9sqrtx=6x+30sqrtx+36`
`<=>2xsqrtx-9x-21sqrtx+36=0` Đến đây tạch rồi :v Ai soi giúp sai chỗ nào với @-@
