Persamaan kuadrat 4x² + 4x + 12= 0 mempunyai akar-akar x1 dan x2. Nilai x1² + x2²=...

Bab Persamaan Kuadrat
Matematika SMP Kelas VIII

4x² + 4x + 12 = 0
a = 4; b = 4; c = 12

(x1)² + (x2)² = (x1 + x2)² - 2 . x1 . x2
                    = (-b/a)² - 2 . c/a
                    = (-4/4)² - 2 . 12/4
                    = 1 - 2 . 3
                    = 1 - 6
                    = -5

Persamaan Kuadrat

4x² + 4x + 12 = 0
x1 + x2 = -b/a = -4/4 = -1
x1 . x2 = c/a = 12/4 = 3

x1² + x2²
= (x1 + x2)² - 2x1x2
= (-1)² - 2.3
= 1 - 6
= -5 ✓