Question

resolva as equações de 2° grau em IR

3+2x²+5x=0

Answer 1

$3+2x^2+5x=0\\\\ a=2;b=5;c=3\\\\\\ \Delta= b^{2} -4ac\to \Delta= 5^{2} -4*2*3\to \Delta= 25-24\to \Delta= 1\\ \\\\x= \frac{-b+- \sqrt{\Delta } }{2a} \to x= \frac{-5+- \sqrt{1} }{2*2} \to x= \frac{-5+- 1 }{4} \to \\\\\\x'= \frac{-5+1 }{4} \to x'= \frac{-4 }{4} \to x'= -1\\ \\\\x''= \frac{-5-1 }{4} \to x''= \frac{-6 }{4} \to x''= \frac{-3 }{2} \to \\\\\\ S=(-1;\frac{-3 }{2})$

Answer 2

3 + 2x² + 5x = 0

2x² + 5x + 3 = 0

a = 2; b = 5; c = 3

Δ = b²  -4ac
Δ = 5² - 4.2.3
Δ = 25 - 8.3
Δ = 25 - 24
Δ = 1

x = - b +/- √Δ = - 5 +/- √1 
         2a              2.2

x = - 5 + 1 = - 4/4 = - 1
           4

x = - 5 - 1 = - 6 (:2) = - 3
           4       4  (:2)      2

R.: x = - 1 e x = - 3
                          2