Question

2x ao quadrado-7x=15

Answer 1

$2x^2-7x=15 \\ \\ 2x^2-7x-15=0$

Tem coeficientes: a=2, b=-7, c=-15
Usando a formula de Bhaskara:
$x_{1,2}= \frac{-b^{+}_{-} \sqrt{b^2-4ac} }{2a} \\ \\ x_{1,2}= \frac{-(-7)^{+}_{-} \sqrt{(-7)^2-4*2*(-15)} }{2*2} \\ \\ x_{1,2}= \frac{7^{+}_{-} \sqrt{49+120} }{4} \\ \\ x_{1,2}= \frac{7^{+}_{-} \sqrt{169} }{4} \\ \\ x_{1,2}= \frac{7^{+}_{-} 13 }{4} \\ \\ x_{1}=\frac{7+13}{4}=5 \\ \\ x_{2} = \frac{7-13}{4}=\frac{-6}{4}=\frac{-3}{2}$

Answer 2

equação do 2° grau

2x² -7x = 15

2x² - 7x - 15=0

a=2
b=-7
c=-15

Δ=b²-4ac
Δ=(-7)²-4(2)(-15)
Δ=49+120
Δ=169

$x= \frac{-b\pm \sqrt{\Delta} }{2a} =~~ \frac{-(-7)\pm \sqrt{169} }{2.(2)} =~~ \frac{7\pm13}{4} \\ \\ x'= \frac{7+13}{4} = \frac{20}{4} =5 \\ \\ x"= \frac{7-13}{4} =- \frac{6}{4} =- \frac{3}{2} \\ \\ S=\{- \frac{3}{2} ,5\}$