Question

http://prntscr.com/b7xx4f

Answer 1

I don't understand it

Answer 2

if a>0 and b,c<0, then using the Cartesio rule we can state that there is a positive root and a negative root

Answer 3

Okay

Answer 4

now, from the general theory, we can write this:
\[{x_1} + {x_2} = - \left( {m + n} \right)\]
where x1 and x2 are the above roots

Answer 5

Okay

Answer 6

or this one:
\[m + n = \left( { - {x_1}} \right) + \left( { - {x_2}} \right)\]

Answer 7

I can eliminate A and B

Answer 8

Im thinking it's C

Answer 9

let's suppose this:
\[{x_1} > 0,\;\quad {x_2} < 0\]

Answer 10

then we can write this:
\[\left| {{x_1}} \right| > \left| {{x_2}} \right|\]

Answer 11

Oh I see, thankyou!

Answer 12

then we can rewrite the above condition in this way:
\[m + n = \left( { - {x_1}} \right) + \left( { - {x_2}} \right) = - \left| {{x_1}} \right| + \left| {{x_2}} \right|\]

Answer 13

Okay, im writing this all down btw

Answer 14

so, \(m+n\) has to be negative since:
\[\left| {{x_1}} \right| > \left| {{x_2}} \right|\]

Answer 15

okay

Answer 16

I think it is option D

Answer 17

Thankyou for the explanation ((: @Michele_Laino

Answer 18

:)

Answer 19

so B,D are true