

Lê Minh Vũ
Giới thiệu về bản thân



































\(0\times\left(7-x\right)=0\)
\(7-x=0\)
\(x=7\) hoặc số bất kì vì 0 nhân với số bất kì nào cũng bằng 0
\(25^2\times2^4\) và \(3^8\)
Ta có:
\(25^2\times2^4=625\times16=10000\)
\(3^8=6561\)
Vì: 10000 > 6561
=> \(25^2\times2^4>3^8\)
\(\left(y-\dfrac{2}{5}\right)\div\dfrac{4}{3}=\dfrac{3}{8}\)
\(\left(y-\dfrac{2}{5}\right)=\dfrac{3}{8}\times\dfrac{4}{3}\)
\(y-\dfrac{2}{5}=\dfrac{1}{2}\)
\(y=\dfrac{1}{2}+\dfrac{2}{5}\)
\(y=\dfrac{9}{10}\)
\(1024\div2^5+140\div\left(38+5^2\right)-7^{23}\div7^{21}\)
\(=1024\div32+140\div\left(38+25\right)-7^{23}\div7^{21}\)
\(=32+140\div63-7^2\)
\(=32+\dfrac{20}{9}-49\)
\(=\dfrac{308}{9}-49\)
\(=-\dfrac{133}{9}\)
b) \(2\dfrac{5}{6}+1\dfrac{2}{3}\div3\dfrac{3}{4}\)
\(=\dfrac{17}{6}+\dfrac{5}{3}\div\dfrac{15}{4}\)
\(=\dfrac{17}{6}+\dfrac{5}{3}\times\dfrac{4}{15}\)
\(=\dfrac{17}{6}+\dfrac{4}{9}\)
\(=\dfrac{153}{54}+\dfrac{24}{54}\)
\(=\dfrac{59}{18}\)
a) \(3\dfrac{1}{2}-1\dfrac{1}{4}\times1\dfrac{5}{6}\)
\(=\dfrac{7}{2}-\dfrac{5}{4}\times\dfrac{11}{6}\)
\(=\dfrac{7}{2}-\dfrac{55}{24}\)
\(=\dfrac{84}{24}-\dfrac{55}{24}\)
\(=\dfrac{29}{24}\)
\(15-\dfrac{x}{2}=\dfrac{3}{7}\)
\(\dfrac{x}{2}=15-\dfrac{3}{7}\)
\(\dfrac{x}{2}=\dfrac{102}{7}\)
\(x\times7=102\times2\)
\(x\times7=204\)
\(x=204\div7\)
\(x=\dfrac{204}{7}\)

\(x\div\dfrac{2}{3}+\dfrac{4}{5}=\dfrac{8}{7}\times\dfrac{7}{10}\)
\(x\div\dfrac{2}{3}+\dfrac{4}{5}=\dfrac{4}{5}\)
\(x\div\dfrac{2}{3}=0\)
\(x=0\)
\(\left(2x-6\right)\times\left(5-x\right)=0\)
\(2x-6=0;5-x=0\)
\(x=3;x=5\)
Vậy: \(x=3;x=5\)
\(4^{14}\times5^{28}\)
\(=4^{14}\times\left(5^2\right)^{14}\)
\(=4^{14}\times25^{14}\)
\(=\left(4\times25\right)^{14}\)
\(=100^{14}\)