ГДЗ по математике 5 класс Ерина Виленкин рабочая тетрадь Часть 1, 2 Часть 1 | Страница 61

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\[\boxed{\mathbf{7}.}\]

\[\textbf{а)}\ 78 \cdot 35 + 22 \cdot 35 =\]

\[= (78 + 22) \cdot 35 = 100 \cdot 35 =\]

\[= 3500\]

\[\textbf{б)}\ 8 \cdot 7 + 8 \cdot 4 = 8 \cdot (7 + 4) =\]

\[= 8 \cdot 11 = 88\]

\[\textbf{в)}\ 42 \cdot 42 - 32 \cdot 42 + 10 \cdot 42 =\]

\[= 42 \cdot (42 - 32 + 10) =\]

\[= 42 \cdot 20 = 840\]

\[\textbf{г)}\ 19 \cdot 17 + 11 \cdot 17 =\]

\[= (19 + 11) \cdot 17 = 30 \cdot 17 = 510\]

\[\textbf{д)}\ 7 \cdot 379 - 6 \cdot 379 =\]

\[= (7 - 6) \cdot 379 = 1 \cdot 379 = 379\]

\[\textbf{е)}\ 19 \cdot 65 + 12 \cdot 65 - 31 \cdot 65 =\]

\[= (19 + 12 - 31) \cdot 65 = 0 \cdot 65 =\]

\[= 0\]

\[\textbf{ж)}\ 16 \cdot 83 + 19 \cdot 83 - 32 \cdot 83 =\]

\[= (16 + 19 - 32) \cdot 83 = 3 \cdot 83 =\]

\[= 249\]

\[\textbf{з)}\ 927 \cdot 18 - 927 \cdot 17 =\]

\[= 927 \cdot (18 - 17) = 927 \cdot 1 =\]

\[= 927\]

\[\textbf{и)}\ 36 \cdot 52 + 54 \cdot 52 =\]

\[= (36 + 54) \cdot 52 = 90 \cdot 52 =\]

\[= 4680\]

\[\boxed{\mathbf{8}.}\]

\[\textbf{а)}\ 13x + 16x = (13 + 16)x =\]

\[= 29x\]

\[\textbf{б)}\ 3b + 8b = (3 + 8)b = 11b\]

\[\textbf{в)}\ a + a + a = (1 + 1 + 1)a =\]

\[= 3a\]

\[\textbf{г)}\ 48p - 27p = (48 - 27)p =\]

\[= 21p\]

\[\textbf{д)}\ 20x + x = (20 + 1)x = 21x\]

\[\textbf{е)}\ 13a + 5a - a =\]

\[= (13 + 5 - 1)a = 17a\]

\[\boxed{\mathbf{9}.}\]

\[\textbf{а)}\ 8x + 8x = 320\]

\[(8 + 8)x = 320\]

\[16x = 320\]

\[x = 320\ :16\]

\[x = 20.\]

\[\textbf{б)}\ 10a - a = 810\]

\[(10 - 1)a = 810\]

\[9a = 810\]

\[a = 810\ :9\]

\[a = 90.\]

\[\textbf{в)}\ 5t + 4t + t = 720\]

\[(5 + 4 + 1)t = 720\]

\[10t = 720\]

\[t = 720\ :10\]

\[t = 72.\]

\[\textbf{г)}\ 15b + 6b - b = 400\]

\[(15 + 6 - 1)b = 400\]

\[20b = 400\]

\[b = 400\ :20\]

\[b = 20.\]