Answer:
b = 40 , c = 70
Explanation:
given a quadratic function in standard form
y = ax² + bx + c ( a ≠ 0 )
then the x- coordinate of the vertex is
x = -
y = 5x² + bx + c ← is in standard form
with a = 5 and b = b , then
x = -
equating to the given x- coordinate of the vertex , that is - 4
-
= - 4 ( multiply both sides by - 10 )
b = 40
then
y = 5x² + 40x + c
substitute (- 4, - 10 ) into the equation and solve for c
- 10 = 5(- 4)² + 40(- 4) + c
- 10 = 5(16) - 160 + c
- 10 = 80 - 160 + c
- 10 = - 80+ c ( add 80 to both sides )
70 = c
then b = 40 and c = 70