# Sebastian

### Why won't 2x^2 change when doing f(-x)?

School is trying to teach me about Descartes' rule of signs, in that how many times the signs (+, -) change in an equation shows how many possible positive zeros there are. To do this, they are showing an equation like this:

f(x) = 2x^5 - 3x^4 + 2x^2 + 5x - 1

and then when they perform f(-x), which, to my knowledge is just flipping the signs on each number, they show an equation like this:

f(-x) = -2x^5 - 3x^4 + 2x^2 - 5x - 1

I cannot wrap my head around why in the world, for some reason, both "2x^2" remains positive after the operation, as well as "-1" remaining negative. Can someone please explain?

2 AnswersMathematics2 months ago### how do you motivate yourself to pursue what you want to do?

every single day i look at the coding books i have next to my computer. Every single day i contemplate trying to really read one and learn what it has to say. Every single day I don't do it. I don't have the motivation or willingness to push myself to do it. I want to create things, I want to create things on the computer. But I just can't do it. What could i possibly do to make myself do that?

3 AnswersProgramming & Design11 months ago