Bài 1:
\(a)8.5-24:12+25.\\ =40-2+25.\\ =63.\\ b)2020^0+3^2.8-8^{19}:8^{17}.\\ =1+72-8^2=9.\\ c)497-2.\left\{150-3.\left[100-3.\left(27+3\right)\right]\right\}.\\ =497-2.\left(150-30\right).\\ =497-240.\\ =257.\)
Bài 2:
\(a)4x+6=18.\\ \Leftrightarrow4x=12.\\ x=3.\\ b)75-5.\left(x+1\right)=50.\\ \Leftrightarrow5.\left(x+1\right)=25.\\ \Leftrightarrow x+1=5.\Leftrightarrow x=4.\\ c)6.5^x+7.5^x=1625.\\ \Leftrightarrow5^x.\left(6+7\right)=1625.\\ \Leftrightarrow5^x=125.\Leftrightarrow5^x=5^3.\Leftrightarrow x=3.\)
\(a,8.5-24:12+25\)
\(=40-24:12+25\)
\(=40-2+25\)
\(=38+25=63\)
\(b,2020^0+3^2.8-8^{19}:8^{17}\)
\(=2020^0+72-8^{19}:8^{17}\)
\(=2020^0+72-8^2\)
\(=72+8^2=136\)
\(c,497-2.\left\{150-3.\left[100-3.\left(27+3\right)\right]\right\}\)
\(=497-2.\left\{150-3.\left[100-3.30\right]\right\}\)
\(=497-2.\left\{150-3.\left[100-90\right]\right\}\)
\(=497-2.\left\{150-3.10\right\}\)
\(=497-2.\left\{150-30\right\}\)
\(=497-2.120\)
\(=497-240=257\)
