Bài 3:
a) \(\left(19x+2\cdot5^2\right):14=\left(13-8\right)^2-4^2\)
\(\Rightarrow\left(19x+2\cdot25\right):14=5^2-4^2\)
\(\Rightarrow\left(19x+50\right):14=9\)
\(\Rightarrow19x+50=9\cdot14\)
\(\Rightarrow19x+50=126\)
\(\Rightarrow19x=126-50\)
\(\Rightarrow19x=76\)
\(\Rightarrow x=76:19\)
\(\Rightarrow x=4\)
b) \(2\cdot3^x=10\cdot3^{12}+8\cdot27^4\)
\(\Rightarrow2\cdot3^x=10\cdot3^{12}+8\cdot27\cdot3^{12}\)
\(\Rightarrow2\cdot3^x=3^{12}\cdot\left(10+8\right)\)
\(\Rightarrow2\cdot3^x=3^{12}\cdot18\)
\(\Rightarrow2\cdot3^x=3^{14}\cdot2\)
\(\Rightarrow3^x=3^{14}\)
\(\Rightarrow x=14\)
c) \(2\cdot3^{x+1}-3^x=135\)
\(\Rightarrow3^x\cdot\left(2\cdot3-1\right)=135\)
\(\Rightarrow3^x\cdot5=135\)
\(\Rightarrow3^x=135:5\)
\(\Rightarrow3^x=27\)
\(\Rightarrow3^x=3^3\)
\(\Rightarrow x=3\)
d) \(15:\left(x+3\right)=\left(3^3+3\right):10\)
\(\Rightarrow15:\left(x+3\right)=\left(27+3\right):10\)
\(\Rightarrow15:\left(x+3\right)=30:10\)
\(\Rightarrow15:\left(x+3\right)=3\)
\(\Rightarrow x-3=15:3\)
\(\Rightarrow x=5+3\)
\(\Rightarrow x=8\)
e) \(4\cdot\left(3x-1\right)^3-5^2=475\)
\(\Rightarrow4\cdot\left(3x-1\right)^3=475+5^2\)
\(\Rightarrow4\cdot\left(3x-1\right)^3=500\)
\(\Rightarrow\left(3x-1\right)^3=500:4\)
\(\Rightarrow\left(3x-1\right)^3=125\)
\(\Rightarrow\left(3x-1\right)^3=5^3\)
\(\Rightarrow3x-1=5\)
\(\Rightarrow3x=6\)
\(\Rightarrow x=\dfrac{6}{3}\)
\(\Rightarrow x=2\)
2:
a: \(=80-4\cdot5^2+3\cdot2^3\)
\(=80-4\cdot25+3\cdot8\)
=80+24-100
=4
b: \(5^6:5^4+2^3\cdot2^2-1^{2017}\)
=5^2+2^5-1
=25+32-1
=56
c: \(=125-2\cdot\left[56-48:8\right]\)
=125-2*50
=125-100
=25
d: \(=23\cdot75+25\cdot\left(10+13\right)+180\)
=23(75+25)+180
=2300+180
=2480
e: \(=2448:\left[119-17\right]\)
=2448/102
=24
f: \(=36\cdot4-4\cdot\left(82-77\right)^2:4-1\)
\(=144-1-5^2\)
=143-25
=118
g: \(=303-3\cdot\left\{\left[655-\left(9+1\right)\cdot64+5\right]\right\}\)
\(=303-3\cdot\left[660-10\cdot64\right]\)
=303-3*20
=303-60
=273