Answer:
-5x^5 -5x^4 +6x^3 -x^2 -7x +20
Explanation:
(2x^5+x^3−3x^4−x+8)−(7x^5+2x^4−12+6x−5x^3+x^2)
Distribute the minus sign
(2x^5+x^3−3x^4−x+8)−7x^5-2x^4+12-6x+5x^3-x^2
Put them in order from largest exponent to smallest exponent
2x^5−7x^5−3x^4-2x^4+5x^3+x^3-x^2-6x−x+8+12
Combine like terms
-5x^5 -5x^4 +6x^3 -x^2 -7x +20
Standard form is from largest exponent to smallest exponent