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#)Giải :
a) \(A=\frac{4^5.9^4-2^6.6^9}{2^{10}.3^8+6^8.20}=\frac{2^{10}.3^8-2^{10}.3^8.3}{2^{10}.3^8+2^8.3^8.2^2.5}=\frac{2^{10}.3^8-2^{10}.3^8.3}{2^{10}.3^8+2^{10}.3^8.5}=\frac{2^{10}.3^8\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}=-\frac{1}{3}\)
\(a,A=\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}\)
\(=\frac{2^{10}.3^8\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}=\frac{-1}{3}\)
Học tốt!!!!!!!!!!!!!
Câu a:
\(\frac{2^{12}.3^5-4^6.9^2}{12^6+8^4.3^5}\)
= \(\frac{2^{12}.3^5-2^{12.3^6}}{2^{12}.3^6+2^{12}.3^5}\)
= \(\frac{2^{12}.3^4.\left(3-1\right)}{2^{12}.3^5.\left(3+1\right)}\)
= \(\frac{2}{3.4}\)
= \(\frac16\)
Câu b:
\(\frac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)
= \(\frac{5^{10}.7^3-5^{10}.7^4}{5^9.7^3+5^9.2^3.7^3}\)
= \(\frac{5^{10}.7^3.\left(1-7\right)}{5^9.7^3.\left(1+8\right)}\)
= \(\frac{5.\left(-6\right)}{9}\)
=- 10/3
Tử số : \(4^5.9^4-2.6^9\)
\(=\left(2^2\right)^5.\left(3^2\right)^4-2.2^9.3^9\)
\(=2^{10}.3^8-2^{10}.3^9\)
Mẫu số : \(2^{10}.3^8+6^8.20\)
\(=2^{10}.3^8+2^8.3^8.2^2.5\)
\(=2^{10}.3^8+2^{10}.3^8.5\)
\(=2^{10}.3^8.6\)
13/50+9/100+41/100+12/50
=(13/50+12/50)+(9/100+41/100)
=1/2+1/2
=1
11) Ta có:
\(\frac{120-0,5.40.5.0,2.20.0,25-20}{1+5+9+...+33+37}\)
\(=\frac{120-\left(0,5.40\right).\left(5.0,2\right).\left(20.0,25\right)-20}{1+5+9+...+33+37}\)
\(=\frac{120-20.1.5-20}{1+5+9+...+33+37}\)
\(=\frac{120-100-20}{1+5+9+...+33+37}\)
\(=\frac{0}{1+5+9+...+33+37}=0\)
Câu 1:
A = (4/9 + 5/6) : (7/8 - 7/12)
A = (8/18 + 15/18) :(21/24 - 14/24)
A = 23/18 : 7/24
A = 23/18 x 24/7
A = 92/21
Câu B = 3/4.8/9.15/16...9999/10000
B = \(\frac{1.3}{2.2}\).\(\frac{2.4}{3.3}\)....\(\frac{99.101}{100.100}\)
B = \(\frac{1.2.3\ldots99}{2.3\ldots100}\). \(\frac{3.4.\ldots101}{2.3\ldots100}\)
B = \(\frac{1}{100}\) x \(\frac{101}{2}\)
B = \(\frac{101}{200}\)
\(B=\frac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}\)\(=\frac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+3^8.2^8.2^2.5}\)\(\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+3^8.2^{10}.5}=\frac{2^{10}.\left(3^8-3^9\right)}{2^{10}\left(3^8+3^8.5\right)}\)
\(=\frac{3^8-3^9}{3^8+3^8.5}=\frac{3^8-3^8.3}{3^8\left(1+5\right)}=\frac{3^8\left(1-3\right)}{3^8\left(1+5\right)}=\frac{1-3}{1+5}=\frac{-2}{6}=\frac{-1}{3}\)
a/ \(\frac{-9}{10}.\frac{5}{14}+\frac{1}{10}.\left(\frac{-9}{2}\right)+\frac{1}{7}.\left(-\frac{9}{10}\right)\)
= \(-\frac{9}{10}.\left(\frac{5}{14}+\frac{1}{7}\right)+\frac{1}{10}.\left(-\frac{9}{2}\right)\)
= \(-\frac{9}{10}.\frac{1}{2}+\frac{1}{10}.\left(-\frac{9}{2}\right)\)
= \(\frac{-9}{20}+\left(-\frac{9}{20}\right)=\frac{-18}{20}=\frac{-9}{10}\)
b/ \(\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{6}+\frac{1}{11}\right).132\)
\(=\left(\frac{1}{2}.132\right)+\left(\frac{1}{3}.132\right)+\left(\frac{1}{4}.132\right)+\left(\frac{1}{6}.132\right)\)\(+\left(\frac{1}{11}.132\right)\)
\(=66+44+33+22+12=177\)
c/ \(-\frac{2}{3}.\left(\frac{8}{9}.\frac{8}{13}-\frac{8}{27}.\frac{8}{13}+\frac{4}{3}.\frac{22}{39}\right)\)
= \(-\frac{2}{3}.\left[\frac{8}{13}\left(\frac{8}{9}-\frac{8}{27}\right)+\frac{88}{117}\right]\)
= \(-\frac{2}{3}.\left(\frac{8}{13}.\frac{16}{27}+\frac{88}{117}\right)\)
= còn lại làm nốt nha! bận ròy
a: \(A=3+3^2+\cdots+3^{50}\)
=>\(3A=3^2+3^3+\cdots+3^{51}\)
=>\(3A-A=3^2+3^3+\cdots+3^{51}-3-3^2-\cdots-3^{50}\)
=>\(2A=3^{51}-3\)
=>\(A=\frac{3^{51}-3}{2}\)
b: Sửa đề: \(B=4^2+4^4+\ldots+4^{100}\)
=>16B=\(4^4+4^6+\cdots+4^{102}\)
=>16B-B=\(4^4+4^6+\cdots+4^{102}-4^2-4^4-\cdots-4^{100}\)
=>15B=\(4^{102}-4^2\)
=>\(B=\frac{4^{102}-4^2}{15}\)
:(
hình như đề bài sai =)))