Đáp án+Giải thích các bước giải:
`a)x=1` $\\$`=>sqrtx=1` $\\$`=>Q=(1+5)/(3-1)=6/2=3` $\\$`b)P=(sqrtx-2)/(sqrtx+3)+(sqrtx+1)/(sqrtx+3)+(x-4sqrtx-9)/(9-x)`$\\$ `P=((sqrtx-2)(sqrtx+3))/((sqrtx-3)(sqrtx+3))+((sqrtx+1)(sqrtx-3))/((sqrtx-3)(sqrtx+3))-(x-4sqrtx-9)/((sqrtx-3)(sqrtx+3))` $\\$`P=(x+sqrtx-6)/((sqrtx-3)(sqrtx+3))+(x-2sqrtx-3)/((sqrtx-3)(sqrtx+3))-(x-4sqrtx-9)/((sqrtx-3)(sqrtx+3))`$\\$ `P=(x+sqrtx-6+x-2sqrtx-3-x+4sqrtx+9)/((sqrtx-3)(sqrtx+3))` $\\$`P=(x+3sqrtx)/((sqrtx-3)(sqrtx+3))` $\\$`P=(sqrtx(sqrtx+3))/((sqrtx-3)(sqrtx+3))` $\\$`P=sqrtx/(sqrtx-3)` ĐPCM$\\$`c)M=P:Q`$\\$ `M=sqrtx/(sqrtx-3):(sqrtx+5)/(3-sqrtx)`$\\$ `M=sqrtx/(sqrtx-3)*(3-sqrtx)/(sqrtx+5)`$\\$ `M=(-sqrtx)/(sqrtx+5)`$\\$ `|M|>1/2`$\\$ `<=>sqrtx/(sqrtx+5)>1/2`$\\$ `<=>sqrtx/(sqrtx+5)-1/2>0` $\\$`<=>(2sqrtx-sqrtx-5)/(2(sqrtx+5))>0` $\\$`<=>(sqrtx-5)/(2sqrtx+10)>0`$\\$ `<=>sqrtx-5>0` (do `2sqrtx+10>=10>0`) $\\$`<=>sqrtx>5`$\\$ `<=>x>25`
