What is the value of c in the equation y = 4x^2 -10x + c if the y-coordinate of the vertex is -7

Question

asked Mar 28, 2020 63.8k views

1 Answer

Harwee · Answer 1 · 2020-04-02T21:33:19+0000

Answer:

Explanation:

Find the x-coordinate of the vertex with this formula:

x=(-b)/(2a)

In this case:

$a=4\\b=-10$

Substituting values, we get:

x=(-(-10))/(2(4))=(5)/(4)

Now we can substitute the coordinates of the vertex into the equation
y = 4x^2 -10x + c and then solve for "c".

Then:

$-7 = 4((5)/(4))^2 -10((5)/(4)) + c\\\\-7+(25)/(4)=c\\\\c=-(3)/(4)$