Question

3- Calcule:
(3x+2)×(x-3)​

Answer 1

$(3x + 2).(x-3)\\ 3x^{2}  - 9x+2x-6\\ 3x^{2} -7x - 6=0$

Δ = b² - 4.a.c

Δ = (-7)² - 4 . 3 . -6

Δ = 49 - 4. 3 . -6

Δ = 121

x = (-b ± √Δ)/2a

x' = -(-7 + √121)/2.3     x'' = -(-7 - √121)/2.3

x' = 18 / 6             x'' = - 4 / 6

x' = 3                     x'' = - 2 / 3

Espero ter ajudado!

Answer 2

$(3x + 2) \times (x - 3) \\ {3x}^{2} - 9x + 2x - 6 \\ {3x}^{2} - 7x - 6 = 0 \\ \\ delta = {b}^{2} - 4 \times a \times c \\ delta = {( - 7)}^{2} - 4 \times 3 \times( - 6) \\ delta = 49 + 72 \\ delta = 121 \\ \\ x = \frac{ - b + - \sqrt{delta} }{2a} \\ x = \frac{ - ( - 7) + - \sqrt{121} }{2 \times 3} \\ x = \frac{7 + - 11}{6} \\ \\ {x}^{1} = \frac{7 + 11}{6} \\ {x}^{1} = \frac{18}{6} \\ {x}^{1} = 3 \\ \\ {x}^{2} = \frac{7 - 11}{6} \\ {x}^{2} = \frac{ - 4}{6}$