Question

определи верные равенства
Верных ответов: 3
–2(m – n) + 3(m + n) = m + 5n
3(m + n) – 2(m – n) = 5m +5n
(3 – 1,2x) – (2,4 + 0,6x) = 0,6 – 1,8x
(0,4 – x) – (1 – x) = –1,4
0,2(a – b) + 2(–b + a) = 2,2a + 2,4b
–(a + b) – 2(a – b) = –3a + b

Answer 1

2. $- 2(m - n) + 3(m + n) = m + 5n \\ - 2m + 2n + 3m + 3n = m + 5n \\ m + 5n = m + 5n$
3. $3(m + n) - 2(m - n) = 5m + 5n \\ 3m + 3n - 2m + 2n = 5m + 5n$
4. m + 5n ≠ 5m+5n
5. $(3 - 1.2x) - (2.4 + 0.6x) = 0.6 - 1.8x \\ 3 - 1.2x - 2.4 - 0.6x = 0.6 - 1.8x \\ - 1.2x - 0.6 x + 1.8x = - 3 + 2.4 + 0.6 \\ 0 = 0$
6. $(0.4 - x) - (1 - x) = - 1.4 \\ 0.4 - x - 1 + x = - 1.4$

-0,6 ≠ - 1,4

5.

$0.2(a - b) + 2(a - b) = 2.2a + 2.4b \\ (a - b)(0.2 + 2) = 2.2a + 2.4b$

2.2a+2.2b ≠ 2.2a+2.4b

6.

$- (a + b) - 2(a - b) = b - 3a \\ - a - b - 2a + 2b = b - 3a \\ b - 3a = b - 3a$