Tính (-2)^5.(-2)^7.2^25 369.(-2)-41.72 Tìm x (2x-12).(x-8)=0 (x-3).(5-x)>0 (9-x).(x-3)<0 08/11/2021 Bởi Madelyn Tính (-2)^5.(-2)^7.2^25 369.(-2)-41.72 Tìm x (2x-12).(x-8)=0 (x-3).(5-x)>0 (9-x).(x-3)<0
Đáp án: `↓↓` Giải thích các bước giải: `(-2)^5 . (-2)^7 . 2^25` `=(-2)^(5+7) . 2^25 = (-2)^12 . 2^25` `= 2^12. 2^25=2^(12+25)` `=2^(37)` `369.(-2)-41.72` `=41.9.(-2)-41.72` `=41.[9.(-2)-72]` `=41.(-90)=-3690` `—-` `(2x-12)(x-8)=0` `=> ` \(\left[ \begin{array}{l}2x-12=0\\x-8=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=6\\x=8\end{array} \right.\) `(x-3)(5-x)>0` `=> x-3; 5-x` cùng dấu \(\left[ \begin{array}{l}\left\{\begin{matrix}x-3>0& \\5-x>0& \end{matrix}\right.\\\left\{\begin{matrix}x-3<0&\\5-x<0& \end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x>3& \\x<5& \end{matrix}\right.\\\left\{\begin{matrix}x<3&\\x>5 & \end{matrix}\right.(KTM)\end{array} \right.\)`=> 3<x<5` `(9-x)(x-3)<0` `=> 9-x; x-3` khác dấu \(\left[ \begin{array}{l}\left\{\begin{matrix}9-x>0& \\x-3<0& \end{matrix}\right.\\\left\{\begin{matrix}9-x<0&\\x-3>0& \end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x<9&\\x<3& \end{matrix}\right.\\\left\{\begin{matrix}x>9&\\x>3 & \end{matrix}\right.\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x>9\\x<3\end{array} \right.\) Vậy `x>9` hoặc `x<3` $\boxed{\text{Khánh Huyền}}$ Bình luận
Đáp án: Giải thích các bước giải: `(-2)^5.(-2)^7.2^{25}` `=(-2)^{12}.2^{25}` `=2^{12}.2^{25}` `=2^{12+25}` `=2^{37}` , `369.(-2)-41.72` `=369.(-2)-2952` `=369.(-2)-369.8` `=369.(-2-8)` `=369.(-10)` `=-3690` , `(2x-12)(x-8)=0` `\to 2x-12=0` hoặc `x-8=0` `*)TH_1:2x-12=0` `\to 2x=12` `\to x=12:2` `\to x=6` `*)TH_2:x-8=0` `\to x=8` Vậy `x=6` hoặc `x=8` , `(x-3)(5-x)>0` `\to` `x-3;5-x ` cung dấu $\to \begin{cases} x-3>0\\5-x>0\\\end{cases}$ $\to\begin{cases} x>3\\-x>-5\\\end{cases}$ $\to\begin{cases} x>3\\x<5\\\end{cases}$ $\to 5>x>3$ Vậy `>5x>3` , `(9-x).(x-3)<0` `to 9-x;x-3` khác dấu `TH_1:` $ \begin{cases} 9-x<0\\x-3>0\\\end{cases}$ $\to\begin{cases} -x>-9\\x>3\\\end{cases}$ $\to\begin{cases} x<9\\x>3\\\end{cases}$ $\to3<x<9$ `TH_2:` $\begin{cases} 9-x>0\\x-3<0\\\end{cases}$ $\to \begin{cases} -x>-9\\x<3\\\end{cases}$ $\to \begin{cases} x<9\\x<3\\\end{cases}$ `\to x<3` Bình luận
Đáp án:
`↓↓`
Giải thích các bước giải:
`(-2)^5 . (-2)^7 . 2^25`
`=(-2)^(5+7) . 2^25 = (-2)^12 . 2^25`
`= 2^12. 2^25=2^(12+25)`
`=2^(37)`
`369.(-2)-41.72`
`=41.9.(-2)-41.72`
`=41.[9.(-2)-72]`
`=41.(-90)=-3690`
`—-`
`(2x-12)(x-8)=0`
`=> ` \(\left[ \begin{array}{l}2x-12=0\\x-8=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=6\\x=8\end{array} \right.\)
`(x-3)(5-x)>0`
`=> x-3; 5-x` cùng dấu
\(\left[ \begin{array}{l}\left\{\begin{matrix}x-3>0& \\5-x>0& \end{matrix}\right.\\\left\{\begin{matrix}x-3<0&\\5-x<0& \end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x>3& \\x<5& \end{matrix}\right.\\\left\{\begin{matrix}x<3&\\x>5 & \end{matrix}\right.(KTM)\end{array} \right.\)`=> 3<x<5`
`(9-x)(x-3)<0`
`=> 9-x; x-3` khác dấu
\(\left[ \begin{array}{l}\left\{\begin{matrix}9-x>0& \\x-3<0& \end{matrix}\right.\\\left\{\begin{matrix}9-x<0&\\x-3>0& \end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x<9&\\x<3& \end{matrix}\right.\\\left\{\begin{matrix}x>9&\\x>3 & \end{matrix}\right.\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x>9\\x<3\end{array} \right.\)
Vậy `x>9` hoặc `x<3`
$\boxed{\text{Khánh Huyền}}$
Đáp án:
Giải thích các bước giải:
`(-2)^5.(-2)^7.2^{25}`
`=(-2)^{12}.2^{25}`
`=2^{12}.2^{25}`
`=2^{12+25}`
`=2^{37}`
,
`369.(-2)-41.72`
`=369.(-2)-2952`
`=369.(-2)-369.8`
`=369.(-2-8)`
`=369.(-10)`
`=-3690`
,
`(2x-12)(x-8)=0`
`\to 2x-12=0` hoặc `x-8=0`
`*)TH_1:2x-12=0`
`\to 2x=12`
`\to x=12:2`
`\to x=6`
`*)TH_2:x-8=0`
`\to x=8`
Vậy `x=6` hoặc `x=8`
,
`(x-3)(5-x)>0`
`\to` `x-3;5-x ` cung dấu
$\to \begin{cases} x-3>0\\5-x>0\\\end{cases}$
$\to\begin{cases} x>3\\-x>-5\\\end{cases}$
$\to\begin{cases} x>3\\x<5\\\end{cases}$
$\to 5>x>3$
Vậy `>5x>3`
,
`(9-x).(x-3)<0`
`to 9-x;x-3` khác dấu
`TH_1:`
$ \begin{cases} 9-x<0\\x-3>0\\\end{cases}$
$\to\begin{cases} -x>-9\\x>3\\\end{cases}$
$\to\begin{cases} x<9\\x>3\\\end{cases}$
$\to3<x<9$
`TH_2:`
$\begin{cases} 9-x>0\\x-3<0\\\end{cases}$
$\to \begin{cases} -x>-9\\x<3\\\end{cases}$
$\to \begin{cases} x<9\\x<3\\\end{cases}$
`\to x<3`