Answer:
[tex]y = 2 {(x + 2)}^{2} + 62[/tex]
Step-by-step explanation:
vertex form is
[tex]y = a {(x - h)}^{2} + k \\ where \: (h. \: k) \: is \: the \: vertex[/tex]
our original equation
[tex]2 {x}^{2} + 8x + 70[/tex]
first we will find the x value using the formula
[tex]x = - \frac{b}{2a} \\ - \frac{8}{2(2)} = - \frac{8}{4} = - 2 \\ x = - 2 = h[/tex]
plug the value of x back into the original equation to solve for y
[tex]y = 2 {x}^{2} + 8x + 70 \\ y = 2 ({ - 2}^{2} ) + 8( - 2) + 70 \\ y = 2(4) - 16 + 70 \\ y = 8 - 16 + 70 \\ y = 78 - 16 \\ y = 62 = k[/tex]
substitute this back into our vertex form and not forgetting the coefficient a = 2
[tex]y = 2 {(x - ( -2))}^{2} + 62 \\ y = 2 {(x + 2)}^{2} + 62[/tex]
