Сократить дробь: 1) [latex] \frac{4a^2+2a+1}{2a+1} [/latex] 2) [latex] \frac{9c^2+3c+1}{3c+1} [/latex] 3) [latex] \frac{25a^2+10a+1}{5a+1} [/latex] 4) [latex] \frac{a+7}{a^2+14a+49} [/latex]