Đáp án:
B3:
2) x=-5
Giải thích các bước giải:
\(\begin{array}{l}
B3:\\
1)15x - 13 = 12x + 8\\
\to 3x = 21\\
\to x = 7\\
2)\dfrac{x}{6} = \dfrac{3}{5} - \dfrac{{43}}{{30}}\\
\to \dfrac{x}{6} = - \dfrac{5}{6}\\
\to x = - 5\\
B4:\\
1)A = \dfrac{{10}}{{24}} - \dfrac{{21}}{{54}} + \dfrac{{11}}{{30}}\\
= \dfrac{5}{{12}} - \dfrac{7}{{18}} + \dfrac{{11}}{{30}}\\
= \dfrac{{5.30 - 7.20 + 11.12}}{{360}}\\
= \dfrac{{150 - 140 + 132}}{{360}} = \dfrac{{71}}{{180}}\\
2)\dfrac{1}{2} - \dfrac{1}{5} - \dfrac{5}{7} + \dfrac{1}{6} - \dfrac{3}{{35}} + \dfrac{1}{3} + \dfrac{1}{{41}}\\
= \dfrac{{3 + 1 + 2}}{6} - \dfrac{{7 + 5.5 + 3}}{{35}} + \dfrac{1}{{41}}\\
= 1 - 1 + \dfrac{1}{{41}} = \dfrac{1}{{41}}
\end{array}\)
