Question

Caucule a soma dos 22 termos de uma Pa,Onde A1=7 e a22=70

Answer 1

a₁ = 7
a₂₂ = 70
S = ?

S₂₂ = (a₁ + a₂₂) * 22 / 2
S₂₂ = (7 + 70) * 22 / 2
S₂₂ = 77 * 22 / 2
S₂₂ = 1694 / 2
S₂₂ = 847

Espero ter ajudado. Valeu!

Answer 2

$S_{n}=\dfrac{(a_{1}+a_{n})\cdot n}{2}\\\\\\S_{22}=\dfrac{(a_{1}+a_{22})\cdot22}{2}\\\\\\S_{22}=(7+70)\cdot11\\\\\\S_{22}=77\cdot11\\\\\\\boxed{\boxed{S_{22}=847}}$