math? is it right?

Not quite.
( 3x^2 - x + 3) - ( 2x^2 - 2x - 4) = 5x^2 -1 x + 7???
Distribute the negative through the second parenthesis:
3x^2 - x + 3 - 2x^2 + 2x + 4
Combine like terms:
x^2 + x + 7

2x(2x^2 - x + 2) = 2^4 - 2x + 4x?
Distribute 2x:
2x(2x^2) - 2x(x) + 2x(2)
4x^3 - 2x^2 + 4x
You were very close, just need some more practice. Take it one step at a time, don't try to combine steps until you've mastered each one separately. You might use more paper and take longer to get to the answer, but you have a better chance of getting it right. I have 40+ credit hours of college math and still show all my steps, keeps me from making "silly" mistakes, like dropping a negative sign or writing the wrong exponent.

i don't know.

1)
(3x^2 - x + 3) - (2x^2 - 2x - 4)
= 3x^2 - x + 3 - 2x^2 + 2x + 4
= 3x^2 - 2x^2 - x + 2x + 3 + 4
= x^2 + x + 7

2)
2x(2x^2 - x + 2)
= 2x*2x^2 - 2x*x + 2x*2
= 2x^4 - 2x^2 + 4x

1. x^2-x+7
2. 4x^3-2x^2+4x

Hmm
Let me introduce myself. My name is Try Andrian from Indonesia.
I think your answers are wrong
The right answer is
1. x^2 - x + 7 (you must minus the 3x^2 with 2x^2, not sum it)

2. 4x^3 - 2x^2 + 4x (you must times the out brackets with all of inbrackets)
Thank you

No it is not right since it is
3x^2 - x +3 -2x^2 +2x +4
=x^2 +x +7
2x(2x^2 - x +2 ) = 4x^3 -2x^2 +4x

( 3x^2 - x + 3) - ( 2x^2 - 2x - 4) =

Okay, on this one remember that the negative sign before the parenthesis applies to everything in the brackets. You have to change the sign of postive to negative and from negative to positive. It ends up looking like:

3x^2-x+3-2x^+2x+4=

And that works out to x^2+x+7

2x(2x^2 - x + 2) =

Here, remember that the first term contains a 2 AND an x and that the x must also be multiplied by the other terms. Remeber to add the powers when multiplying like terms. It ends up as:

(4x^3)-(2x^2)+4x

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

subtract alike terms, subtracting a negative is really adding a positive.

then you multiply 2x by everything in the parenthesis the number before the x is multiplied and the exponents are added

Wrong! Who told you 3-2=5?
It should be x^2 +x +7.
Second too!
It should be 4x^3 -2x^2+4x.
And you need not write 1x, Just write x. OK?