$$\text { If } f ( x ) = 2 x ^ { 2 } + 1 \text { and } g ( x ) = x - 1 \text {, find } f + g , f g \text {, and their domains. }$$

$$\text { If } f ( x ) = 2 x ^ { 2 } + 1 \text { and } g ( x ) = x - 1 \text {, find } f + g , f g \text {, and their domains. }$$