Creo que son estos los que me pediste por el mensajito, bueno hay te van las respuestas :
9.
- x² - 3x = 0 x(x - 3) = 0 x = 0 x = 3
10.
- 6x² + 42x = 0 6x(x + 7) = 0 6x = 0 x = 0 x + 7 = 0 x = - 7
11.
- x² + ax = 0 x(x + a) = 0 x = 0 x = - a
12.
- (x 2)(x 3) = 6 x² - 5x + 6 - 6 = 0 x² - 5x = 0 x(x - 5) = 0 x = 0 x = 5
13.
- (x 2)(x + 5) = 9x + 10 x² + 3x - 10 - 9x - 10 = 0 x² - 6x - 20 = 0 x = 8.
38 x = - 2.
38
14.
- (2x + 6)(2x 6) = (2x + 9)(3x 4) 4x² - 36 = 6x² - 8x + 27x - 36 2x² + 19x = 0 x(2x + 19) = 0 x = 0 x = - 19 / 2
15.
- (x + 3)² 8x 9 = 0 x² + 6x + 9 - 8x - 9 = 0 x² - 2x = 0 x(x - 2) = 0 x = 0 x = 2
16.
- (x + 4)² + (x 3)² = (x + 5)² x² + 8x + 16 + x² - 6x + 9 = x² + 10x + 25 x² - 8x = 0 x(x - 8) = 0 x = 0 x = 8
17.
- (x + 13)² = (x + 12)² + (x 5)² x² + 26x + 169 = x² + 24x + 144 + x² - 10x + 25 x² - 2x² + 26x - 14x = 0 - x² + 12x = 0 x² - 12x = 0 x(x - 12) = 0 x = 0 x = 12
ESPERO TE SEA UTIL, SALUDOS.