Question

tìm x;

1a)  (   \(\frac{2}{11x13}\)+\(\frac{2}{13x15}\)+\(\frac{2}{15x17}\)+\(\frac{2}{17x19}\)+\(\frac{2}{19x21}\))x462-x=19

2b)  187-{[497-(8*x+11):x]:3-78=150

3c)  19,96 + 4,19 - 24,15 : (x:\(\frac{1}{4}\)-\(\frac{1}{4}\))=23,15 

       ( giải nhanh, đúng và đầy đủ nhé)^^^

Answer 1

1. \(\left(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+\frac{2}{17.19}+\frac{2}{19.21}\right)\times462-x=19\)

\(\left(\frac{13-11}{11.13}+\frac{15-13}{13.15}+\frac{17-15}{15.17}+\frac{19-17}{17.19}+\frac{21-19}{19.21}\right)\times462-x=19\)

\(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+\frac{1}{17}-\frac{1}{19}+\frac{1}{19}-\frac{1}{21}\right)\times462-x=19\)

\(\left(\frac{1}{11}-\frac{1}{21}\right)\times462-x=19\)

\(\frac{10}{231}\times462-x=19\)

\(20-x=19\)

\(x=20-19\)

\(x=1\)

Answer 2

2.b \(187-[[497-(8\times x+11)\div x]\div3-78]=150\)

​​\(187-[[497-(\frac{8\times x}{x}+\frac{11}{x})]:3-78]=150\)

\(187-[(497-8-\frac{11}{x}):3-78]=150\)

\(187-[(489-\frac{11}{x}):3-78]=150\)

\(187-[\frac{489}{3}-\frac{33}{x}-78]=150\)

\(187-[163-\frac{33}{x}-78]=150\)

\(187-85+\frac{33}{x}=150\)

\(102+\frac{33}{x}=150\)

\(\frac{33}{x}=150-102\)

\(\frac{33}{x}=48\)

\(x=\frac{48}{33}=\frac{16}{11}\)