x²+4x+ 10 =0
7x² - 9 =0
3x =10x²
4x² = 17
0 =9x - 7x²
3 =7x²
5x²- 1 = 0
3x²+3x+ 20 =0
x²+3x =0
x²+3x =30
0 =x - x²
3x²+6 =0
7x²+5x = 0
x² = -x+ 8
6 = x²
8x² = 9x
x²+ 20 =5x
x²+3x =15
