1) x²-2x+1-2x-6=x²+4x+4-17x
x²-x²-4x-4x+17x=4-1+6
-8x+17x=9
9x=9
x=9/9
x=1
2)x²-25-x²+6x-9=x-9
6x-x=-9+9+25
5x=25
x=25/5
x=5
4)x²-9+x+1=2(x²-10+25)+3x-1
x²+x-8=2x²-20x+50+3x-1
x²-2x²+x+20x-3x=-1+50+8
-x²+18x= 57
-x²+18x-57=0
faci si tu delta , altfel daca nu da x-ul ceva e gresit din exercitiu . calculele sunt corecte.
5)9x²+6x+1-4x²+4x-1=5(x²-8x+16)+8x+4
5x²+10x=5x²-40x+80+8x+4
42x=84
x=84/42
x=2
