(x – 3)² – 10 = 15
↓
[tex] {x}^{2} - 6x + 9 - 10 = 15[/tex]
[tex] {x}^{2} - 6x - 1 = 15[/tex]
[tex] {x}^{2} - 6x - 15 = 0[/tex]
[tex] {x}^{2} + 2x - 8x - 1 - 15 = 0[/tex]
[tex] {x}^{2} + 2x - 8x - 16 = 0[/tex]
[tex]x \times (x + 2) - 8x - 16 = 0[/tex]
[tex]x \times (x + 2) - 8(x + 2) = 0[/tex]
[tex](x + 2) \times (x - 8) = 0[/tex]
[tex]x + 2 = 0[/tex]
[tex]x - 8 = 0[/tex]
so,
[tex]x1 = - 2[/tex]
[tex]x2 = 8[/tex]
