The line of symmetry for the quadratic equation y = ax^2 + 8x - 3 is x = 4. what is the value of "a"?

a = - 1

Step-by-step explanation:

given a quadratic in standard form : y = ax² + bx + c : a ≠ 0

Then the x-coordinate of the vertex is

• = -

The line of symmetry passes through the parabola, hence x-coordinate is 4

y = ax² + 8x - 3 is in standard form

with a = a, b = 8 and c = - 3, hence

- = 4 ( multiply both sides by 2a

- 8 = 8a ( divide both sides by 8 )

a = - 1

D(h) = 55h - 2000

1670 m

Step-by-step explanation:

Given :

Starting elevation, D = - 2000 m (2000 m below sea level)

Rate, h = 55 m per hour.

The slope - intercept relation :

y = mx + c

m = slope = rate of change

c = intercept

In the scenario given :

-2000 = intercept

55 = rate of change

D(h) = 55h - 2000

After 6 hours :

D(6) = 55(6) - 2000

D(6) = - 1670 m