5/5-1/5

=4/5

272/34+1/34

=273/33

2/5+1/4

=8/20+5/20=13/20

\(\dfrac{1}{1}-\dfrac{1}{5}=\dfrac{5}{5}-\dfrac{1}{5}=\dfrac{4}{5}\)

\(\dfrac{8}{1}+\dfrac{1}{34}=\dfrac{272}{34}+\dfrac{1}{34}=\dfrac{273}{34}\)

\(\dfrac{2}{5}+\dfrac{1}{4}=\dfrac{8}{20}+\dfrac{5}{20}=\dfrac{13}{20}\)

đề:)?

quy đồng à

a: 9/7>1>5/6

b: 4/7=12/21>8/21

c: 2/5=12/30

1/3=10/30

1/2=15/30

mà 10<12<15

nên 1/3<2/5<1/2

\(C=\dfrac{-1}{5}+\left(\dfrac{1}{-5}\right)^2+\left(-\dfrac{1}{5}\right)^3+...+\left(-\dfrac{1}{5}\right)^{99}\)

=>\(5\cdot C=-1+\left(-\dfrac{1}{5}\right)+\left(-\dfrac{1}{5}\right)^2+...+\left(-\dfrac{1}{5}\right)^{98}\)

=>\(5\cdot C-C=\left(-1\right)-\left(-\dfrac{1}{5}\right)^{99}\)

=>\(4C=-1+\dfrac{1}{5^{99}}=\dfrac{-5^{99}+1}{5^{99}}\)

=>\(C=\dfrac{-5^{99}+1}{4\cdot5^{99}}\)

(x-3y)^2006+(y+4)^2008=0

=>x-3y=0 và y+4=0

=>x=3y và y=-4

=>x=3*(-4)=-12 và y=-4

247 X 328 = 81016

35864:175= 35864/175

\(\dfrac{7}{5}x\dfrac{2}{5}=\dfrac{14}{25}\)

\(\dfrac{3}{4}+\dfrac{5}{4}:\dfrac{1}{4}x\dfrac{1}{2}=\dfrac{3}{4}+5x\dfrac{1}{2}=\dfrac{5}{2}\)

7/5 x 2/5 = 14/25

3/4 + 5/4 : 1/4 x 1/2 = 13/4

\(4,7\div0,25+5,3\times4\)

\(=18,8+21,2\)

\(=40\)

\(3\times\left(a-2\right)+150=240\)

\(3\times\left(a-2\right)=90\)

\(a-2=30\)

\(a=32\)

\(\dfrac{1}{9}+a+\dfrac{7}{12}=\dfrac{17}{18}\)

\(\dfrac{1}{9}+a=\dfrac{13}{36}\)

\(a=\dfrac{1}{4}\)

\(\left(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}+\dfrac{1}{6}\times\dfrac{1}{7}+\dfrac{1}{7}\times\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)

\(\left(\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\right)\times a=\dfrac{9}{16}\)

\(\left(\dfrac{1}{2}-\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)

\(\dfrac{3}{8}\times a=\dfrac{9}{16}\)

\(a=\dfrac{3}{2}\)

a) \(\dfrac{8}{x}+\dfrac{1}{5}=\dfrac{2}{5}+\dfrac{1}{3}=\dfrac{11}{15}\)

\(\dfrac{8}{x}=\dfrac{11}{15}-\dfrac{1}{5}=\dfrac{8}{15}\)

\(x=\dfrac{8\times15}{8}=15\)

B) \(\left(x-\dfrac{3}{5}\right)=\dfrac{5}{8}\times\dfrac{1}{5}=\dfrac{1}{8}\)

\(x=\dfrac{1}{8}+\dfrac{3}{5}=\dfrac{29}{40}\)

\(1,\)

\(a,\sqrt{6-2\sqrt{5}}=\sqrt{\sqrt{5^2}-2.\sqrt{5}.1+1}=\sqrt{\left(\sqrt{5}-1\right)^2}=\left|\sqrt{5}-1\right|=\sqrt{5}-1\)

\(b,\sqrt{8+2\sqrt{7}}=\sqrt{\sqrt{7^2}+2.\sqrt{7}.1+1}=\sqrt{\left(\sqrt{7}+1\right)^2}=\left|\sqrt{7}+1\right|=\sqrt{7}+1\)

\(2,\)

\(a,\sqrt{\left(\sqrt{10}-3\right)^2}-\sqrt{10}\)

\(=\left|\sqrt{10}-3\right|-\sqrt{10}\)

\(=\sqrt{10}-\sqrt{10}-3\)

\(=-3\)

\(b,\sqrt{\left(5+\sqrt{7}\right)^2}-\sqrt{8-2\sqrt{7}}\)

\(=\left|5+\sqrt{7}\right|-\sqrt{\left(\sqrt{7}-1\right)^2}\)

\(=5+\sqrt{7}-\left|\sqrt{7}-1\right|\)

\(=5+\sqrt{7}-\sqrt{7}+1\)

\(=6\)

toán 5 mà khó thế bn

\(A=\dfrac{1}{2}\times\left(\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{2011}-\dfrac{1}{2013}\right)=\dfrac{1}{2}\times\left(\dfrac{1}{5}-\dfrac{1}{2013}\right)=\dfrac{1004}{10065}\)

ủa alo

tụi chị ghê, thui để em trả lời cho =3
C

gòi bị bơ lun gòi