Answer:
C. [tex]13x^2-10x+17[/tex]
Step-by-step explanation:
[tex]\left(3x^2+11x+20\right)+\left(10x^2-21x-3\right)[/tex]
Remove brackets:
[tex]3x^2+11x+20+10x^2-21x-3[/tex]
Group similar terms together:
[tex]3x^2+10x^2+11x-21x+20-3[/tex]
Add/subtract the [tex]x^2:[/tex]
[tex]13x^2+11x-21x+20-3[/tex]
Add/subtract the [tex]x:[/tex]
[tex]3x^2-10x+20-3[/tex]
Add/subtract the numbers:
[tex]13x^2-10x+17[/tex]
