1) Thực hiện các phép tính sau: a) 3/8 + 2^2 - 3/8 b) (-2)^2 + căn 36 - căn 9 + |-5| 2) Tìm y, biết: a) y - {1}/{2} = 3/4 b) | y - 1/3| - 1 {1}/{4} = 0,25
1. a)\(\frac{3}{8} + {2^2} - \frac{3}{8}\)\( = \left( {\frac{3}{8} - \frac{3}{8}} \right) + 4\)
\[ = 0 + 4 = 4\]
b) \({\left( { - 2} \right)^2} + \sqrt {36} - \sqrt 9 + \left| { - 5} \right|\)
\[ = 4 + 6--3 + 5\]
\[ = 12\].2.
a) \(y - \frac{1}{2} = \frac{3}{4}\)
\(\frac{2}{3}y = \frac{3}{4} + \frac{1}{2}\)
\(\frac{2}{3}y = \frac{5}{4}\)
\(y = \frac{{15}}{8}\).
b) \(\left| {y - \frac{1}{3}} \right| - 1\frac{1}{4} = 0,25\)
\(\left| {y - \frac{1}{3}} \right| = \frac{1}{4} + \frac{5}{4}\)
\(\left| {y - \frac{1}{3}} \right| = \frac{3}{2}\)
• TH1: • TH2:
\(y - \frac{1}{3} = \frac{3}{2}\) \(y = \frac{3}{2} + \frac{1}{3}\) \(y = \frac{{11}}{6}\) | \(y - \frac{1}{3} = - \frac{3}{2}\) \(y = - \frac{3}{2} + \frac{1}{3}\) \(y = \frac{{ - 7}}{6}\) |
Vậy \[y \in \left\{ {\frac{{11}}{6};\,\,\frac{{ - 7}}{6}} \right\}\].