Someone, please help I'll give 10 points and brainliest to the person who answers first

C.

Step-by-step explanation:

5x-12y+8x+2xy+4xy=(5x+8x)-12y+6xy=13x-12y+6xy

a4 - 3a2 - 1

step-by-step explanation:

step   1   :

equation at the end of step   1   :

  ((a4) -   3a2) -   1

step   2   :

trying to factor by splitting the middle term

2.1     factoring   a4-3a2-1  

the first term is,   a4   its coefficient is   1 .

the middle term is,   -3a2   its coefficient is   -3 .

the last term, "the constant", is   -1  

answer: all the values are within because it has a pattern that repeats from -6 to 4.

good luck!