Bila a dan bAkar persamaan x²—2x—5=0, nilai dari 1/a²+1/β²

jawab
x² -2x - 5= 0
a =1
b = -2
c =  -5
α+β = -b/a = 2
α.β  = c/a = - 5

1/α² + 1/β² =  (α²+β²)/(αβ)² = [(α+β)² - 2αβ] / (αβ)²
= (2² - 2(-5))/ (-5)²
= (4 +10)/(25)
= 14/25