8 x 4 + 8 x 3 - 8 x 2 + 8 x 5 = ?
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8 x 1 = 8 8 x 2 = 16 8 x 3 = 24 8 x 4 = 32
1 x 8 = 8 2 x 8 = 16 3 x 8 = 24 4 x 8 = 32
8 x 5 = 40 8 x 6 = 48 8 x 7 = 56 8 x 8 = 64
5 x 8 = 40 6 x 8 = 48 7 x 8 = 56 8 x 9 = 72
![](https://rs.olm.vn/images/avt/0.png?1311)
mình đang cần gấp câu trả lời ,bạn nào giải được nhanh k luôn ,hứa đấy
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8 x 2 + 8 = 16 + 8
= 24
8 x 4 + 8 = 32 + 8
= 40
8 x 6 + 8 = 48 + 8
= 54
8 x 3 + 8 = 24 + 8
= 32
8 x 5 +8 = 40 + 8
= 48
8 x 7 + 8 = 56 + 8
= 64
![](https://rs.olm.vn/images/avt/0.png?1311)
8 x 1 = 8 8 x 3 = 24 8 x 5 = 40 8 x 7 = 56 8 x 9 = 72
8 x 2 = 16 8 x 4 = 32 8 x 6 = 48 8 x 8 = 64 8 x 10 = 80
![](https://rs.olm.vn/images/avt/0.png?1311)
b) Ta có: \(5^{x+4}-3\cdot5^{x+3}=2\cdot5^{11}\)
\(\Leftrightarrow2\cdot5^{x+3}=2\cdot5^{11}\)
\(\Leftrightarrow x+3=11\)
hay x=8
c) Ta có: \(2\cdot3^{x+2}+4\cdot3^{x+1}=10\cdot3^6\)
\(\Leftrightarrow18\cdot3^x+12\cdot3^x=10\cdot3^6\)
\(\Leftrightarrow30\cdot3^x=30\cdot3^5\)
Suy ra: x=5
d) Ta có: \(6\cdot8^{x-1}+8^{x+1}=6\cdot8^{19}+8^{21}\)
\(\Leftrightarrow6\cdot\dfrac{8^x}{8}+8^x\cdot8=6\cdot8^{19}+64\cdot8^{19}\)
\(\Leftrightarrow8^x\cdot\dfrac{35}{4}=70\cdot8^{19}\)
\(\Leftrightarrow8^x=8^{20}\)
Suy ra: x=20
![](https://rs.olm.vn/images/avt/0.png?1311)
8 x 1 = 8
8 x 5 = 40
8 x 0 = 0
8 x 8 = 64
8 x 2 = 16
8 x 4 = 32
8 x 6 = 48
8 x 9 =72
8 x 3 = 24
8 x 7 = 56
8 x 10 = 80
![](https://rs.olm.vn/images/avt/0.png?1311)
Học sinh tự nhẩm và ghi như sau:
8 x 3 = 24
8 x 2 = 16
8 x 4 = 32
8 x 1 = 8
8 x 5 = 40
8 x 6 = 48
8 x 7 = 56
0 x 8 = 0
8 x 8 = 64
8 x 10 = 80
8 x 9 = 72
8 x 0 = 0
![](https://rs.olm.vn/images/avt/0.png?1311)
`(3xx4xx7)/(5xx3xx4)=7/5`
`(2xx5xx6xx8)/(6xx2xx8xx9)=5/9`
`(4xx5xx6)/(3xx10xx8)= (4xx5xx6)/(3xx5xx2xx4xx2)= 6/(3xx2xx2)= 6/(6xx2)=1/2`
\(a,\dfrac{3\times4\times7}{5\times3\times4}=\dfrac{7}{5}\)
\(b,\dfrac{2\times5\times6\times8}{6\times2\times8\times9}=\dfrac{5}{9}\)
\(c,\dfrac{4\times5\times6}{3\times10\times8}=\dfrac{2}{4}=\dfrac{1}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =7/8:(2/9-18+1/36)-5/12
=-7/142-5/12=-397/852
b: =3/7(4/9+5/9:6/12)=2/3
c: =5^8(16/31-47/31)+1/3=-5^8+1/3
d: =7/2(3/8+5/8:4/15)=609/64
![](https://rs.olm.vn/images/avt/0.png?1311)
a,
\(5^{x+4}-3.5^{x+3}=2.5^{11}\)
\(\Rightarrow5^{x+3}\left(5-3\right)=2.5^{11}\)
\(\Rightarrow5^{x+3}2=2.5^{11}\)
\(\Rightarrow5^{x+3}=5^{11}\)
\(\Rightarrow x+3=11\)
\(\Rightarrow x=8\)
b, (Check lai xem de sai o dau khong nhe)
\(3.5^{x+2}+4.5^{x+3}=19.5^{10}\)
Dat 5x ra ben ngoai
\(\Rightarrow5^x.5^23+5^x:5^{-3}.4\)
\(\Rightarrow5^x\left(5^2.3+5^{-3}.4\right)\)
\(\Rightarrow5^x\left(5^{-3}.5^5.3+5^{-3}.4\right)\)
\(\Rightarrow5^x[5^{-3}\left(5^53+4\right)\)
\(\Rightarrow5^x[5^{-3}\left(3125.3+4\right)\)
\(\Rightarrow5^x\left(5^{-3}\right).9379\)
=> Khong tim duoc gia tri cua x \(\Rightarrow x\in\varnothing\)
8 x 4 + 8 x 3 - 8 x 2 + 8 x 5
= 8 x ( 4 + 3 - 2 + 5 )
= 8 x ( 7 - 2 + 5 )
= 8 x ( 5 + 5 )
= 8 x 10
= 80