Rút gọn M=\(\frac{a^{30}+a^{20}+a^{10}+1}{a^{2042}+a^{2032}+a^{2022}+a^{2012}+a^{30}+a^{20}+a^{10}+1}\)
Rút gọn phân thức:
\(\frac{a^{30}+a^{20}+a^{10}+1}{a^{2042}+a^{2032}+a^{2022}+a^{2012}+a^{30}+a^{20}+a^{10}+1}\)
\(=\dfrac{a^{20}\left(a^{10}+1\right)+\left(a^{10}+1\right)}{\left(a^{10}+1\right)\left(a^{2032}+a^{2012}+a^{20}+1\right)}\)
\(=\dfrac{a^{20}+1}{\left(a^{20}+1\right)\left(a^{2012}+1\right)}=\dfrac{1}{a^{2012}+1}\)
\(a^{30}b^{30}+b^{30}c^{30}+c^{30}a^{30}=3a^{20}b^{20}c^{20} tính A= (1+\dfrac{a^{10}}{b^{10}}).(1+\dfrac{b^{10}}{c^{10}}).(1+\dfrac{c^{10}}{^{10}})\)
a,rút gọn (x^40+x^30+x^20+x^10+1)/(x^45+x^40+...+x^5+1)
b,a>b>0 và 3*a^2+3*b^2=10ab
tính giá trị P=(b-a)/(b+a)
Rút gọn:
A =\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{20}\right)\)
B = \(1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{2012}}\)
So sánh :
\(A=\frac{20^{10}+1}{20^{10}-1}vàB=\frac{20^{10}-1}{20^{10}-3}\)
rút gọn biểu thức :
A=1+1/2+1/22+1/23+...+1/22012
so sánh :
A=2010+1/2010-1 và B=2010-1/2010-3
Phân số nào dưới đây rút gọn thành phân số 2/3
A 20/50
B 14/21
C 10/30
D25/30
Rút gọn rồi tính: a)5/8+18/27 b)12/20+6/18 c)8/12+20/30 đ)10/12+12/36
b: 12/20+6/18=3/5+1/3=9/15+5/15=14/15
c: 8/12+20/30=2/3+2/3=4/3
d: 10/12+12/36=5/6+2/6=7/6
Thu gọn biểu thức sau : \(A=\frac{1}{10}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}-\frac{1}{72}-\frac{1}{90}\)
\(A=\frac{1}{10}-\left(\frac{1}{20}+\frac{1}{30}+....+\frac{1}{90}\right)=\frac{1}{10}-\left(\frac{1}{4.5}+\frac{1}{5.6}+.....+\frac{1}{9.10}\right)\)
\(=\frac{1}{10}-\left(\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...-\frac{1}{10}\right)=\frac{1}{10}-\left(\frac{1}{4}-\frac{1}{10}\right)=\frac{1}{5}-\frac{1}{4}=\frac{-1}{20}\)
\(A=\frac{1}{10}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}-\frac{1}{72}-\frac{1}{90}\)
\(A=\frac{1}{10}-\left(\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+...+\frac{1}{90}\right)\)
\(A=\frac{1}{10}-\left(\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{9.10}\right)\)
\(A=\frac{1}{10}-\left(\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\right)\)
\(A=\frac{1}{10}-\left[\left(\frac{1}{4}-\frac{1}{10}\right)-\left(\frac{1}{5}-\frac{1}{5}\right)-...-\left(\frac{1}{9}-\frac{1}{9}\right)\right]\)
\(A=\frac{1}{10}-\frac{1}{4}+\frac{1}{10}\)
\(A=\frac{1}{5}-\frac{1}{4}\)
\(A=-\frac{1}{20}\)
rút gọn biểu thức sau:
M = 1/ a2 - 5a + 6 + 1 / a2 - 7a + 12 + 1 / a2 - 9a + 20 + 1 / a2 - 11a +30
\(M=\frac{1}{a^2-5a+6}+\frac{1}{a^2-7a+12}+\frac{1}{a^2-9a+20}+\frac{1}{a^2-11a+30}\)
\(M=\frac{1}{\left(a-2\right)\left(a-3\right)}+\frac{1}{\left(a-3\right)\left(a-4\right)}+\frac{1}{\left(a-4\right)\left(a-5\right)}+\frac{1}{\left(a-5\right)\left(a-6\right)}\)
\(M=\frac{1}{a-2}-\frac{1}{a-3}+\frac{1}{a-3}-\frac{1}{a-4}+\frac{1}{a-4}-\frac{1}{a-5}+\frac{1}{a-5}-\frac{1}{a-6}\)
\(M=\frac{1}{a-2}-\frac{1}{a-6}\)