Enter an expression in the box to write a quadratic function given the vertex (7,-4) and the point (5, 8).

Step-by-step explanation:

The vertex form of an equation of the parabola:  

                                                       f(x) = a(x - h)² + k

the vertex is (7, -4)  ⇒   h = 7,  k = -4

so:

     f(x) = a(x - 7)² + (-4)

    f(x) = a(x - 7)² - 4

The parabola goes through the point (5, 8) ⇒   x=5,  f(x)=8

8 = a(5 - 7)²  - 4

8 = a(-2)²  - 4

+4           +4

12  = 4a

÷4       ÷4

a = 3

It means the equation of the parabola in vertex form:

                               f(x) = 3(x - 7)² - 4

vbbv

step-by-step explanation:

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)