tolong bantuanya lagi jawab 2 soal mtk log sama persamaan kuadrat

27. 2x^2 + 4x - 5 = 0

x1^2 + x2^2 = (x1 + x2)^2 - 2x1x2
= (-2)^2 - 2(-5/2)
= 4 + 5
= 9
Jawaban: B

21. 3 log a + 3 log (akar a)^4 - 3 log a^-2
= 3 log a + 3 log a^2 - 3 log a^-2
= 3 log (a × a^2 / a^-2)
= 3 log (a^3 × a^2)
= 3 log a^5
= 5 (3 log a)
Jawaban: B

dari soal dik a=2 b=4  c=-5
x1+x2=-b/a
x1+x2=-4/2
x1*x2=c/a
          =-5/2
1/x1+1/x2=(x1=x2)/(x1*x2)
                 =(-4/2)/(-5/2)
                 = -4/2.2/-5
  1/x1+1/x2  =4+5
                    =9