Question

Jika x1 dan x2 , akar-akar persamaan kuadrat x^2 - 2x + 4 = 0

tentukan:

a) 1/X1 + 1/X2
b) X1^2 + X2^2

Answer 1

X1+x2 = -b/a = 2
x1.2 = c/a = 4
.
a) 1/x1 + 1/x2 = (x1+x2)/(x1.x2) = 2/4 = 1/2
b) x1^2 +x2^2 =(x1 +x2)^2 - 2 x1x2 = (2^2) - 2(4) =4-8 = -4