2. Приведение подобных слагаемых:
- а) \( -2a + 4b - 7a - 9b = (-2a - 7a) + (4b - 9b) = -9a - 5b \)
- б) \( -4m + 2,5 + 7 + 26m - 6,4 = (-4m + 26m) + (2,5 + 7 - 6,4) = 22m + (9,5 - 6,4) = 22m + 3,1 \)
- в) \( -x - 2\frac{1}{9}y + 3\frac{5}{27}y - 4\frac{8}{9}y - \frac{8}{27}x + 5\frac{3}{4}x = (-x - \frac{8}{27}x + 5\frac{3}{4}x) + (-2\frac{1}{9}y + 3\frac{5}{27}y - 4\frac{8}{9}y) \)
- \( = (x(-1 - \frac{8}{27} + 5\frac{3}{4})) + (y(-2\frac{1}{9} + 3\frac{5}{27} - 4\frac{8}{9})) \)
- \( = (x(-1 - \frac{32}{108} + \frac{69}{27})) + (y(-2\frac{3}{27} + 3\frac{5}{27} - 4\frac{24}{27})) \)
- \( = (x(-\frac{108}{108} - \frac{32}{108} + \frac{276}{108})) + (y(-\frac{54}{27} + \frac{81}{27} - \frac{108}{27})) \)
- \( = x\frac{136}{108} + y(-\frac{81}{27}) = x\frac{34}{27} - 3y \)
Ответ: а) -9a - 5b; б) 22m + 3,1; в) \(\frac{34}{27}x - 3y\).