Question

1) considere a PA (1; 3 + x;17-4x) B) qual é a PA?

Answer 1

$\Large\boxed{\begin{array}{l}\sf(1,3+x,17-4x)\\\sf a_2=a_1+r\\\sf 3+x=1+r\\\sf r=3+x-1\\\sf r=x+2\\\sf a_3=a_1+2r\\\sf a_3=a_2+r\\\sf 17-4x=3+x+x+2\\\sf x+x+4x=17-3-2\\\sf 6x=12\\\sf x=\dfrac{12}{6}=2\\\sf (1,2+3,17-4\cdot2)\\\sf(1,5,17-8)\\\sf PA(1,5,9\dotsc)\end{array}}$