Bài tập 5 trang 36 SGK Toán 8 Chân trời sáng tạo Tập 2 - CTST

a) Ta có: \(\frac{5x-3}{4}=\frac{x+2}{3}\)

\(\Leftrightarrow \frac{3(5x-3)}{12}=\frac{4(x+2)}{12}\)

\(\Leftrightarrow 15x - 9 = 4x + 8\)

\(\Leftrightarrow 15x - 4x = 8 + 9\)

\(\Leftrightarrow 11x = 17\)

\(\Leftrightarrow x=\frac{17}{11}\)

b) Ta có: \(\frac{9x+5}{6}=1-\frac{6+3x}{8}\)

\(\Leftrightarrow \frac{4(9x+5)}{24}=\frac{24-3(6+3x)}{24}\)

\(\Leftrightarrow 36x + 20 = 24 - 18 - 9x\)

\(\Leftrightarrow 36x + 9x = 24 - 18 -20\)

\(\Leftrightarrow 45x = -22\)

\(\Leftrightarrow x=\frac{-22}{45}\)

c) Ta có: \(\frac{2(x+1)}{3}-\frac{1}{2}=\frac{1+3x}{4}\)

\(\Leftrightarrow \frac{8(x+1)-6}{12}=\frac{3(1+3x)}{12}\)

\(\Leftrightarrow 8x + 8 - 6 = 3 + 9x\)

\(\Leftrightarrow 8x - 9x = 3 + 6 - 8\)

\(\Leftrightarrow -x = 1\)

\(\Leftrightarrow x = -1\)

d) Ta có: \(\frac{x+3}{5}-\frac{2}{3}x=\frac{3}{10}\)

\(\Leftrightarrow \frac{3(x+3)}{15}-\frac{10x}{15}=\frac{3}{10}\)

\(\Leftrightarrow 3x +9-10x=\frac{9}{2}\)

\(\Leftrightarrow -7x=-\frac{9}{2}\)

\(\Leftrightarrow x=\frac{9}{14}\)

-- Mod Toán 8 HỌC247