Step-by-step explanation:
you will see, this is totally easy. so, once you understand that principle, I am sure you will agree with me that this costs more time putting it in here than just doing it yourself in the future.
you need to consider for addition and subtraction every variable combined with an exponent a different thing, a fruit for example.
you know exactly what to do, when you are being asked to add 3 apples to 2 apples, right ?
or, when are are asked to add 4 apples and 2 pears to 3 apples and 2 pears.
in the first case we simply get 5 (2+3) apples.
in the second case we get 7 (3+4) apples and 4 (2+2) pears.
and nothing else happens here.
we could call x² apples, y² pears, y³ plums, x kiwis, t strawberries, t² raspberries. and the constants could be another fruit or grams of sugar.
now, we simply combine the "fruits" that belong together. there is nothing more to this.
5x² + 3y³ - 4x² = x² - 3y³ (because 5-4 for x²)
y³ + 2y³ - 8 + 2 = 3y³ - 6 (1+2 for y³ and -8+2 constant)
9 - 3x - 4x + 2x - 12 = -5x - 3
-6t + 4t² - 6 + 7t - 4t² = t - 6 (4-4 for t², -6+7 for t)
