Question

b) x^2-9=0 c) x^2-6x=0

Answer 1

${x}^{2} - 9 = 0 \\ {x}^{2} = 9 \\ x = \sqrt{9} \\ x = 3$

${x}^{2} - 6x = 0 \\ {b}^{2} - 4ac = \\ {(- 6)}^{2} - 4 \times 1 \times 0 = \\ 36 - 0 = 36 \\ \frac{ - ( - 6) + - \sqrt{36} }{2 \times 1} = \\ \\ \frac{6 + - 6}{2} = \\ x1 = \frac{6 + 6}{2} = \frac{12}{2} = 6 \\ x2 = \frac{6 - 6}{2} = \frac{0}{2} = 0$

Espero ter lhe ajudado!