Question

Va rog un raspuns intreg si corect!

Answer 1

b5= 48

b8=384

bn= b1*q^(n-1)

b5= b1*q^4

b8=b1*q^7

___________(:)

1/q^3= 48/384

1/q^3=1/8 ⇒ q^3=8 ⇒q=2

b1*q^4= 48

b1*16 = 48 ⇒b1=3

Answer 2

Explicație pas cu pas:

progresie geometrică:

$\begin{cases} b_{5} = 48 \\ b_{8} = 384 \end{cases} \iff \begin{cases} b_{1} \cdot q^{4} = 48 \\ b_{1} \cdot q^{7} = 384 \end{cases}$

$\dfrac{q^{7}}{q^{4}} = \dfrac{384}{48} \iff q^{3} = 8 = {2}^{3} \\ \implies q = 2$

$b_{1} \cdot 2^{4} = 48 \implies \bf b_{1} = 3$