Question

calcule a soma dos 7 termos da p.g (8,4,2,1,1/2)​

Answer 1

Explicação passo a passo:

a1= 8

a2 =4

a3 = 2

q = 4/8 = 1/2 ou 0,5 >>>>

S7 = a1 * ( q^n - 1 )/ ( q - 1 )

S7 = 8 *[ ( 0,5 )^7 -1 ] / ( 0,5 - 1)

S7 = 8 * [ 0,0078125 - 1]/ ( - 0,5)

S7 = 8 * [ - 0,9921875 ]/ - 0,5

S7 = - 7,9375 / - 0,5

S7 = 15,875 >>>>

Answer 2

$> resolucao \\ \\ \geqslant progressao \: geometrica \\ \\ q = \frac{a2}{a1} \\ q = \frac{4}{8} \\ q = \frac{1}{2} \\ \\ \\ sn = \frac{a1(1 - q {}^{n} )}{1 - q} \\ \\ sn = \frac{8(1 - ( \frac{1}{2}) {}^{7} )}{1 - \frac{1}{2} } \\ \\ sn = \frac{8(1 - \frac{1}{128} )}{ \frac{1}{2} } \\ \\ sn = \frac{8 \times \frac{127}{128} }{ \frac{1}{2} } \\ \\ sn = \frac{ \frac{1016}{128} }{ \frac{1}{2} } \\ \\ sn = \frac{1016}{128} \times \frac{2}{1} \\ \\ sn = \frac{2032 \div 16}{128 \div 16} \\ \\ sn = \frac{127}{8} \\ \\ > < > < > < > < > < > < > < > >$