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45 . 94 - 2 . 69/210 . 38 + 68 . 20\(=\frac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}=\frac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+2^{10}.3^8.5}\)\(=\frac{2^{10}.3^8.\left(1-3\right)}{2^{10}.3^8.\left(1+5\right)}=\frac{-2}{6}=\frac{-1}{3}\)
1)\(\frac{4^6.45}{2^4}=\frac{\left(2^2\right)^6.45}{2^4}=\frac{2^{12}.45}{2^4}=2^8.45=256.45=11520\)
2)\(\frac{8^5.16^3}{4^{13}}=\frac{8^5.\left(4^2\right)^3}{4^{13}}=\frac{8^5.4^6}{4^{13}}=\frac{8^5}{4^7}=\frac{\left(8^2\right)^2.8}{\left(4^3\right)^2.4}=\frac{64^2.8}{64^2.4}=\frac{8}{4}=2\)
3)Cái này bạn tự làm vì dễ rồi
4)\(\frac{45^{10}.5^{20}}{75^{15}}=\frac{\left(3^2.5\right)^{10}.5^{20}}{\left(5^2.3\right)^{15}}=\frac{3^{20}.5^{10}.5^{20}}{5^{30}.3^{15}}=\frac{3^{20}.5^{30}}{5^{30}.3^{15}}=3^5=243\)
Chúc bạn học tốt
Trả lời:
1,\(\frac{4^6\times45}{2^4}=\frac{\left(2^2\right)^6\times45}{2^4}\)
\(=\frac{2^{12}\times45}{2^4}\)
\(=2^8\times45\)
\(=256\times45\)
\(=11520\)
2,\(\frac{8^5\times16^3}{4^{13}}=\frac{\left(2^3\right)^5\times\left(2^4\right)^3}{\left(2^2\right)^{13}}\)
\(=\frac{2^{15}\times2^{12}}{2^{26}}\)
\(=\frac{2^{27}}{2^{26}}\)
\(=2\)
3,\(\frac{2^{10}\times13+2^{10}\times65}{2^8\times104}=\frac{2^{10}\times\left(13+65\right)}{2^8\times104}\)
\(=\frac{2^{10}\times78}{2^8\times104}\)
\(=\frac{2^2\times3}{4}\)
\(=\frac{4\times3}{4}\)
\(=3\)
4,\(\frac{45^{10}\times5^{20}}{75^{15}}=\frac{\left(5\times9\right)^{10}\times5^{20}}{\left(3\times25\right)^{10}}\)
\(=\frac{\left(5\times3^2\right)^{10}\times5^{20}}{\left(3\times5^2\right)^{15}}\)
\(=\frac{5^{10}\times3^{20}\times5^{20}}{3^{15}\times5^{30}}\)
\(=\frac{5^{30}\times3^{20}}{3^{15}\times5^{30}}\)
\(=3^5=243\)
Học tốt
- \(\frac{4^6.3^4.9^5}{6^{12}}=\frac{\left(2^2\right)^6.3^4.\left(3^2\right)^5}{\left(2.3\right)^{12}}=\frac{2^{12}.3^4.3^{10}}{2^{12}.3^{12}}=\frac{2^{12}.3^{14}}{2^{12}.3^{12}}=3^2=9\)
- \(\frac{3^{10}.11+9^5.5}{3^9.2^4}=\frac{3^{10}.11+\left(3^2\right)^5.5}{3^9.16}=\frac{3^{10}.11+3^{10}.5}{3^9.16}=\frac{3^{10}.\left(11+5\right)}{3^9.16}=\frac{3^{10}.16}{3^9.16}=3\)
- 2100 - 299 - 298 - ... - 22 - 2
= 2100 - (299 + 298 + ... + 22 + 2)
Đặt A = 299 + 298 + ... + 22 + 2
2A = 2100 + 299 + ... + 23 + 22
2A - A = (2100 + 299 + ... + 23 + 22) - (299 + 298 + ... + 22 + 2)
A = 2100 - 2
Ta có:
2100 - 299 - 298 - ... - 22 - 2
= 2100 - (2100 - 2)
= 2100 - 2100 + 2
= 0 + 2
= 2
- 38 : 36 + (22)4 : 29
= 32 + 28 : 29
\(=9+\frac{1}{2}\)
\(=\frac{18}{2}+\frac{1}{2}=\frac{19}{2}\)
a)\(\frac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}=\frac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(3.2\right)^8.2^2.5}=\frac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+3^8.2^8.2^2.5}=\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+3^8.2^{10}.5}\)
\(=\frac{2^{10}.3^8.\left(1-3\right)}{2^{10}.3^8.\left(1+5\right)}=\frac{-2}{6}=\frac{-1}{3}\)
b) đặt A=2100 - 299 + 298 - 297 +...+ 22 - 2
=>2A=2101-2100+299-298+...+23-22
=>2A+A=2101-2100+299-298+...+23-22+2100 - 299 + 298 - 297 +...+ 22 - 2
=>3A=2101-2
=>A=\(\frac{2^{101}-2}{3}\)
Lời giải:
Đặt \(A=2^2+4^2+6^2+8^2+...+60^2\)
\(A=(2.1)^2+(2.2)^2+(2.3)^2+(2.4)^2+...+(2.30)^2\)
\(=2^2(1^2+2^2+3^2+4^2+...+30^2)\)
Sử dụng hằng đẳng thức đáng nhớ:
\((1+1)^3=1^3+3.1^2+3.1+1\)
\((2+1)^3=2^3+3.2^2+3.2+1\)
\((3+1)^3=3^3+3.3^2+3.3+1\)
..............
\((30+1)^3=30^3+3.30^2+3.30+1\)
Cộng theo vế:
\(2^3+3^3+...+31^3=(1^3+2^3+..+30^3)+3(1^2+2^2+...+30^2)+3(1+2+3+...+30)+30\)
\(\Leftrightarrow 31^3=1+3(1^2+2^2+...+30^2)+3.\frac{30(30+1)}{2}+30\)
\(\Leftrightarrow 1^2+2^2+...+30^2=9455\)
Do đó: \(A=2^2(1^2+2^2+3^2+...+30^2)=4.9455=37820\)