Bantu isi yaa kak buat besok

11. x^2 +6x -7 = 0
(x+7)(x-1) = 0
x + 7 = 0 dan x - 1 = 0
x= -7 dan x = 1

12. akarnya 4 dan -6
(x-x1)(x-x2)=0
(x-4)(x-(-6))=0
(x-4)(x+6)=0
x^2-4x+6x-24=0
x^2+2x-24 = 0

13.2x^2+8x-4=0
a=2,b=8,c=-4

x1+x2= -b/a = -8/2 = -4
x1.x2 = c/a = -4/2 = -2

jadi
1/x1 + 1/x2 = x1+x2/x1.x2 = -4/-2 = 2