1)7x² = 21|:7
x² = 3
|x| = ✓3
x = ±✓3
2)6x²+x = 0
x(6x+1) = 0
[x = 0
[6x+1 = 0
6x = -1|:6
x = -1/6
3)x² = -8x
x²+8x = 0
x(x+8) = 0
[x+8 = 0
x = -8
4)x²+8x+16 = 0
(x+4)² = 0
x+4 = 0
x = -4
1)7x² = 21|:7
x² = 3
|x| = ✓3
x = ±✓3
2)6x²+x = 0
x(6x+1) = 0
[x = 0
[6x+1 = 0
6x = -1|:6
x = -1/6
3)x² = -8x
x²+8x = 0
x(x+8) = 0
[x = 0
[x+8 = 0
x = -8
4)x²+8x+16 = 0
(x+4)² = 0
x+4 = 0
x = -4