[ Answer ]
[tex]\boxed{10x^{2} \ + \ 8x \ + \ 1}[/tex]
[ Explanation ]
Simplify: ([tex]2x^{2}[/tex] + x + 4) + (-3 + 7x + [tex]8x^{2}[/tex])
Remove Parenthesis
[tex]2x^{2}[/tex] + x + 4 + -3 + 7x + [tex]8x^{2}[/tex]
Group Like Terms
[tex]2x^{2}[/tex] + [tex]8x^{2}[/tex] + 8 + 7x + 4 - 3
Add Similar Elements: x + 7x = 8x
[tex]2x^{2}[/tex] + [tex]8x^{2}[/tex] + 8x + 4 - 3
Add Similar Elements
[tex]2x^{2}[/tex] + [tex]8x^{2}[/tex] = [tex]10x^{2}[/tex]
[tex]10x^{2}[/tex] + 8x + 4 - 3
Add / Subtract The Numbers: 4 - 3 = 1
[tex]10x^{2}[/tex] + 8x + 1
[tex]\boxed{[ \ Eclipsed \ ]}[/tex]
