Jika x1 dan x2 adalah akar – akar persamaan kuadrat 2x2 - 6x - 8 = 0

A. x1 + x2

B. x1.x2

C. (x1 + x2 )2

D. 1/x1 + 1/x2

E. x1/x2 + x2/x1

Tentukan nilai diskriminan dari pernyataan berikut

A. x2 -5x + 6 = 0

B. 4×2 +8x + 4 = 0

C. x2 + 4x + 8 = 0

Jika x1 dan x2 adalah akar – akar persamaan kuadrat 2x2 - 6x - 8 = 0

Jika x1 dan x2 adalah akar – akar persamaan kuadrat 2×2 – 6x – 8 = 0

Penjelasan dengan langkah-langkah:

$2 {x}^{2} - 6x - 8 = 0 \ a = 2 \ b = - 6 \ c = - 8$

$x1 + x2 = - frac{b}{a} \ = - frac{ - 6}{2} \ = 3$

$x1.x2 = frac{c}{a} \ = frac{ - 8}{2} \ = - 4$

${(x1 + x2)}^{2} = {3}^{2} = 9$

$frac{1}{x1} + frac{1}{x2} = frac{x2 + x1}{x1.x2} = - frac{3}{4}$

$frac{x1}{x2} + frac{x2}{x1} = frac{ {x1}^{2} + {x2}^{2} }{x2.x1} = frac{ {(x1 + x2)}^{2} - 2x1.x2}{x1.x2} \ = frac{ {3}^{2} - (2.- 4)}{ - 4} \ = - frac{17}{4}$

${x}^{2} - 5x + 6 = 0 \ d = {b}^{2} - 4ac \ d = {( - 5)}^{2} - 4.1.6 \ d = 25 - 24 \ d = 1$

$4 {x}^{2} + 8x + 4 = 0 \ d = {b}^{2} - 4ac \ d = {8}^{2} - 4.4.4 \ d = 64 - 64 \ d = 0$

${x}^{2} + 4x + 8 = 0\ d = {b}^{2} - 4ac \ d = {4}^{2} - 4.1.8 \ d = 16 - 32 \ d = - 16$