Question

resolva:

a)2x²+7x-4-x-1=
b)x-1.2x²+7-4=

Answer 1

a) 2x² + 6x - 5 = 0
Δ = b2 - 4.a.c 
Δ = 62 - 4 . 2 . -5 
Δ = 36 - 4. 2 . -5 
Δ = 76
Há 2 raízes reais.

x = (-b +- √Δ)/2a

x' = (-6 + √76)/2.2   
x'' = (-6 - √76)/2.2

x' = 2,717797887081348 / 4   
x'' = -14,717797887081348 / 4

x' = 0,679449471770337   
x'' = -3,679449471770337

B) -2x² + x + 3 = 0
    2x² - x - 3 = 0

Δ = b2 - 4.a.c 
Δ = -12 - 4 . 2 . -3 
Δ = 1 - 4. 2 . -3 
Δ = 25
Há 2 raízes reais.

x = (-b +- √Δ)/2a

x' = (--1 + √25)/2.2   
x'' = (--1 - √25)/2.2

x' = 6 / 4  
x'' = -4 / 4

x' = 1,5   
x'' = -1