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What are the zeros and a -intercepts for the function below?
f(x) = 2x² + 14x + 20

1 Answer

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Explanation:

the zeros are the x-intercepts. because these are x values, when y (= f(x)) = 0.

a quadratic equation has 2 zeros (even if they are equal or complex numbers).

a quadratic equation

ax² + bx + c = 0

can always be solved by

x = (-b ± sqrt(b² - 4ac))/(2a)

in our case

x = (-14 ± sqrt(14² - 4×2×20))/(2×2) =

= (-14 ± sqrt(196 - 160))/4 =

= (-14 ± sqrt(36))/4 = (-14 ± 6)/4

x1 = (-14 + 6)/4 = -8/4 = -2

x2 = (-14 - 6)/4 = -20/4 = -5

these are the 2 zeros (x-intercepts).

if you need the explicit points :

(-5, 0) and (-2, 0)

the y-intercept is the y-value when x = 0

y = 2×0² + 14×0 + 20 = 20

the explicit point : (0, 20)

User Daniel Leiszen
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