$\left\{\begin{array}{ccc}y=-7x+2\\y=9x-1\end{array}\right\Rightarrow 9x-1=-7x+2\\\\9x-1=-7x+2\ \ \ |+1\\9x=-7x+3\ \ \ |+7x\\16x=3\ \ \ \ |:16\\x=\dfrac{3}{16}\\\\\text{substitute the value of x to the second equation}\\\\y=9\cdot\dfrac{3}{16}-1\\\\y=\dfrac{27}{16}-\dfrac{16}{16}\\\\y=\dfrac{11}{16}\\\\\text{The solution is}\ \left(\dfrac{3}{16};\ \dfrac{11}{16}\right)$

3 0

3 years ago

Find the sum of this infinite geometric series where a1=0.3 and r=0.55

Lisa [10]

Hello, Marymack!

We know that in a geometric sequence defined by $\mathsf{a_1}$ and $\mathsf{r}$ , the sum can be calculated the following way:

$\mathsf{S_n = \dfrac{a_1}{1-r}}\\ \\ \\ \\ \mathsf{S_n = \dfrac{0.3}{1-0.55}}\\ \\ \\ \mathsf{S_n = \dfrac{0.3}{0.45}}\\ \\ \\ \boxed{\mathsf{S_n = \dfrac{2}{3}=0.666...}}$

3 0

3 years ago

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