Question

-5x² + 15x + 20 = 0 ???

Answer 1

-5xao quadrado +15x=0-20
-5x elevado a 2 +15x =-20

Answer 2

x=  (-b +/- √b²-4.a.c) / 2.a 
x= -15 +/- √15²-4.(-5).20 /2.-5
x'=-15 + √625 / -10
x'= 10/-10
x'= -1
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x"= -15-25/-10
x"= -40/-10
x"= 4