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a) \(2^{4x}-3^{2x}=144-164:41\)
\(\Leftrightarrow16^x-9^x=144-4\)
\(\Leftrightarrow\) ......
bjan tự tính tiếp đc òi
A)9-25=(7-x)-(25-7)
9-25=7-x-25-7
9-25=(7-7)-(x+25)
9-25=0-x-25
9-25=x-25
25+25=9+x
50=9+x
x=50-9
x=41
23.27.24=23+7+4=214
23.24:25=23+4-5=27
(-3)+(-125)+(-25)
=-128+(-25)
=-153
25+(-38)=25-38=-13
126+159=285
120+(-135)+200
=120-135+200
=-15+200
=185
2^3x2^7=2^10x2^4=2^14=16384
2^3x2^4=2^7:2^5=2^2=4
1300-(150.2+(900+90):9)=1300-(150.2+990:9)=1300-(300+11)=1300-311=989
(-3) + (-125)+(-25)= -(3+125+25)= -153
25 + (-38)= -(38-25)= - 13
(126)+159=285
(120)+(-135)+200= -(135-120) + 200= (-15) + 200= +(200-15)=185
A=-[-506+732-(-2000)]-(506-1732)
=-506-732+2000-506+1738
=(-506+506)+(1732-732)-2000
= 0 + 1000 -2000
= -1000
B=1037+{743-[1031-(+57)]}
=1037+{743-1031-57}
=1037+743-1031-57
=(1037-1031)+(743+57)
= 6 + 800
= 806
C=(125.73-125.75):(-25.2)
=[125.(73-75)]:(-50)
=[125.(-2)]:(-50)
= (-250) :(-50)
= 5
D=-25.(35+147)+35.(25+147)
=-25.35-25.147+35.25+35.147
=-25.147+35.147
=147.(-25+35)
=147.10
= 1470
E=125.9.(-4).(-8).25.7
=[125.(-8)].[(-4).25].9.7
=-1000.(-100).9.7
=-100000.9.7
=-9000000.7
=-63000000
G=(-3)2+(-5)3:|-5|
=9.(-125):5
=9-(-25)=-16
mk cũng làm giống ý kiến của bn Lê Phan Bảo Như.....^^
a) \(5\left(x+7\right)-10=2^3\cdot5\)
\(\Rightarrow5\left(x+7\right)-10=40\)
\(\Rightarrow5\left(x+7\right)=40+10\)
\(\Rightarrow x+7=\dfrac{50}{5}\)
\(\Rightarrow x+7=10\)
\(\Rightarrow x=10-7\)
\(\Rightarrow x=3\)
b) \(9x-2\cdot3^2=3^4\)
\(\Rightarrow9x-18=81\)
\(\Rightarrow9x=81+18\)
\(\Rightarrow9x=99\)
\(\Rightarrow x=\dfrac{99}{9}\)
\(\Rightarrow x=11\)
c) \(5^{25}\cdot5^{x-1}=5^{25}\)
\(\Rightarrow5^{x-1}=5^{25}:5^{25}\)
\(\Rightarrow5^{x-1}=1\)
\(\Rightarrow5^{x-1}=5^0\)
\(\Rightarrow x-1=0\)
\(\Rightarrow x=1\)
\(\left(25+2x\right)^3.5-3^2=4^2\\ \left(25+2x\right)^3.5=4^2+3^2=25\\ \left(25+2x\right)^3=\dfrac{25}{5}=5\)
Tới khúc này với toán 6 anh thấy số xấu quá em
a, \(390-\left(x-7\right)=13^2:12\)
\(390-\left(x-7\right)=\) \(\dfrac{169}{12}\)
\(x-7=390-\dfrac{169}{12}\)
\(x-7=\dfrac{4511}{12}\)
\(x=\dfrac{4511}{12}+7\)
\(x=\dfrac{4595}{12}\)
Vậy ...
b, \(\left(x-35.2^2\right):7=3^3-24\)
\(\left(x-35.4\right):7=27-24\)
\(\left(x-140\right):7=3\)
\(\Leftrightarrow\left(x-140\right)=3.7\)
\(\Leftrightarrow x-140=21\)
\(\Leftrightarrow x=161\)
Vậy .....
c) \(x-6:2-\left(4^2.3-24\right):2:6=3\)
\(x-3-\left(16.3-24\right):2:6=3\)
\(x-3-\left(48-24\right):2:6=3\)
\(x-3-24:2:6=3\)
\(x-3-2=3\)
\(x=3+2+3\)
\(x=8\)
Vậy ......
d) \(4x-5=5+5^2+5^3+.....+5^{99}\)
Đặt :
\(A=5+5^2+.........+5^{99}\)
\(\Leftrightarrow5A=5^2+5^3+..........+5^{100}\)
\(\Leftrightarrow5A-A=\left(5^2+5^3+......+5^{100}\right)-\left(5+5^2+....+5^{99}\right)\)
\(\Leftrightarrow4A=5^{100}-5\)
\(\Leftrightarrow A=\dfrac{5^{100}-5}{4}\)
\(\Leftrightarrow4x+5=\dfrac{5^{100}-5}{4}\)
Đến đây thì sao nữa nhỉ ?
e) \(\left(2x-1\right)^4=625\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(2x-1\right)^4=5\\\left(2x-1\right)^4=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
Vậy ....
\(3^2\left(x-4\right)-25=35\)
\(\Rightarrow9\left(x-4\right)=35+25\)
\(\Rightarrow9x-36=60\)
\(\Rightarrow9x=60+36\)
\(\Rightarrow9x=96\)
\(\Rightarrow x=\frac{96}{9}=\frac{32}{3}\)
trả lời:
\(x=\frac{32}{3}\)
hok tốt nhé
tk nhé