Question

2x²-7=15 equação do 2° grau
Por favor conta completa usando a forma de bhaskara

Answer 1

$\displaystyle \mathsf{2x^2 - 7x = 15}\\ \displaystyle \mathsf{2x^2 - 7x - 15 = 0}\\ \\ \displaystyle \mathsf{a = 2; b =-7; c = -15}$

$\displaystyle \mathsf{\Delta = b^2 - 4.a.c}\\ \displaystyle \mathsf{\Delta = (-7)^2 - 4.(2).(-15)}\\ \displaystyle \mathsf{\Delta = 49 + 120}\\ \displaystyle \mathsf{\Delta = 169}$

$\displaystyle \mathsf{x = \frac{-b \: \pm \sqrt{\Delta}}{2a}}\\ \\ \displaystyle \mathsf{x = \frac{-(-7) \: \pm \sqrt{169}}{2.2}}\\ \\ \displaystyle \mathsf{x = \frac{7 \: \pm 13}{4}}$

$\displaystyle \mathsf{x' = \frac{7 + 13}{4}}\\ \\ \displaystyle \mathsf{x' = \frac{20}{4}}\\ \\ \displaystyle \mathsf{x' = 5}\\ \\ \\ \displaystyle \mathsf{x'' = \frac{7 - 13}{4}}\\ \\ \displaystyle \mathsf{x'' = \frac{-6 \: \div 2}{4 \: \div 2}}\\ \\ \displaystyle \mathsf{x'' = \frac{-3}{2}}$

Resposta: $\displaystyle \boxed{\mathsf{x_1 = 5 \: ou \: x_2 = \frac{-3}2{}}}$

Answer 2

Bom dia!



2x² - 7x = 15
2x² - 7x - 15 = 0



∆ = b² - 4.a.c


a = 2
b = -7
c = -15



∆ = (-7)² - 4.2.(-15)
∆ = 49 + 120
∆ = 169


x = -b ± √∆/2.a


x = -(-7) ± √169/2.2

x = 7 ± 13/4

x' = 7 - 13/4 = -6/4 = -3/2

x" = 7 + 13/4 = 20/4 = 5


S={ -3/2, 5 }



★Espero ter ajudado! tmj