Question

determine o 1° termo e a razão de cada PA na qual a5-a2=15 e a3+a8=49

Answer 1

$\left \{ {{a_5 - a_2=15} \atop {a_3 + a_8=49}} \right. \\ \\ \\ \left \{ {{a_1 + 4r - a_1 + r=15} \atop {a_1 + 2r + a_1 + 7r=49}} \right. \\ \\ \\ \left \{ {{5r=15} \atop {2a_1 + 9r=49}} \right. \\ \\ \\ \left \{ {{r=3} \atop {2a_1 + 9(3)=49}} \right. \\ \\ \\ 2a_1 + 27 = 49 \\ 2a_1 = 49 - 27 \\ 2a_1 = 22 \\ a_1 = 11$