1. - (7x²-5x+3)-(7x²-5)= 2. - (3x+1)+(-3x²-3x+1)= 3. - (a+3b)+(3a-3b)= 4. - a²-5ab-b²-(a²+b²)= 5. - (x+y-z)-(x-y)+(x-y+z)=
1. 7x²–5x+3-7x²+5=8-5x 2.3x+1-3x²-3x+1=2-3x² 3.a+3b+3a-3b=4a 4.a⁴–5ab–b²–a²-b²=a⁴–5ab–a²-2b² 5.x+y–z-x+y+x-y+z=x+y