Find the sum of these polynomials. (x9 - x + 8) + (10x9 + 7) = a. 10x18 - x + 15 b. 10x9 - x + 15 c. 11x9 - x + 15 d. 11x18 - x + 15

The correct answer is:  [C]:  " 11x⁹  − x  + 15 "  .

Explanation: 

Given:

    "  (x⁹ − x + 8) + (10x⁹ + 7)  " ;    Simplify/ Add.

We can rewrite this as:
 
"  1x⁹ − 1x + 8 + 10x⁹ + 7 = ?

 →  {The "1" is implied; since "1", multiplied by any value, results in the exact same value.}.

Combine the "like terms" :

  + 1x⁹  + 10x⁹ = 11x⁹ ; 
 
  + 8 + 7 = 15 ; 

and we are left with:  " − 1x " ; which we can rewrite as:  " −x " ; 

So, we can write our answer as:


→  " 11x⁹  − x  + 15 "  ;

   →  which is:  "Answer choice:  [C]:  " 11x⁹  − x  + 15 "  ;