Question

calcule o 20° termo p.a, sabendo que a1= 20 e r=10

Answer 1

a1 =20    razão = 10

Pn=a1+(n-1)*r

P20=20+(20-1)*10

P20=20+19*10

P20=20+190

P20=210

Resposta: o 20º termo da p.a = 210

Answer 2

$\begin{gathered}\LARGE\boxed{\begin{array}{lr}\rm a_n=a_1+(n-1)\cdot r \\\rm a_ {20}=20+(20-1)\cdot 10 \\\rm a_ {20}=20+19\cdot 10 \\\rm a_ {20}=20+190 \\\rm a_ {20}=210 \end{array}}\end{gathered}$