hjhj :3 e sẽ thử sức mik xem sao :33

bữa sau em dừng cho dấu " ` " vào chữ nha khó nhìn lắm :")

`(-7)/15 . 11/13 + 7/15 . (-2)/13 +8/15`

`=7/15 . (-11)/13 + 7/15 . (-2)/13 +8/15`

`=7/15 . [(-11)/13+( (-2)/13)]+8/15`

`=7/15 . (-1)+8/15`

`=(-7)/15+8/15`

`=1/15`

`------------`

`(-4)/11 . 2/5 + 6/11 . (-3)/10`

`=((-4)/11+6/11).(2/5+(-3)/10)`

`=2/11 . (4/10+(-3)/10)`

`=2/11 . (-1)/10`

`=1/11 . (-1)/5`

`=-1/55`

`a.@ P=(x+5)(ax^2 + bx +25)`

`P=ax^3 bx^2 +25x + 5ax^2 + 5bx + 125`

`P=ax^3(b+5a)x^2 +(25+5b)x +125`

`b.`

Ta có :`@ P=Q`

`=>ax^3(b+5a)x^2 +(25+5b)x +125=x^3 +125`

\(\Leftrightarrow\left\{{}\begin{matrix}a=1\\b+5a=0\\25+5b=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=1\\b=-5\end{matrix}\right.\)

`=>` Vậy...

`3/4 =1/3xx ( a- 2/5): 7/5`

`=> 1/3xx ( a- 2/5): 7/5 =3/4`

`=> ( a- 2/5): 7/5 =3/4:1/3`

`=> ( a- 2/5): 7/5 =3/4 xx3`

`=>( a- 2/5): 7/5 =9/4`

`=>a- 2/5=9/4xx7/5`

`=>a- 2/5=63/20`

`=>a=63/20+2/5`

`=>a=63/20+8/20`

`=>a=71/20`