\[\boxed{\text{675.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
Пояснение.
Решение.
\[\textbf{а)}\ 14x + 21y = 7 \cdot (2x + 3y)\]
\[\textbf{б)}\ 15a + 10b = 5 \cdot (3a + 2b)\]
\[\textbf{в)}\ 8ab - 6ac = 2a(4b - 3c)\]
\[\textbf{г)}\ 9xa + 9xb = 9x(a + b)\]
\[\textbf{д)}\ 6ab - 3a = 3a(2b - 1)\]
\[\textbf{е)}\ 4x - 12x^{2} = 4x(1 - 3x)\]
\[\textbf{ж)}\ m^{4} - m^{2} = m²(m^{2} - 1)\]
\[\textbf{з)}\ c³ + c^{4} = c³(1 + c)\]
\[\textbf{и)}\ 7x - 14x^{3} = 7x(1 - 2x^{2})\]