Let's create expressions and equations to model this situation. Let Anthony's age be a.
"Jim is 3 times as old as his cousin, Anthony." Jim's age is 3a.
"The difference in their age is 18." 3a - a = 18
How old is Jim?
Let's solve the above equation for a to first find Anthony's age.
3a - a = 18
2a = 18
a = 9
Remember, Jim's age is represented by the expression 3a. Substitute Anthony's age, 9, into the expression to find Jim's age.
3a
3(9)
27
Answer:
Jim is 27 years old.
The vertex is exactly half way between directrix and focus. In this case the vertex is (8,-7)
(h,k)
P is the distance between the vertex and either the directrix or focus, in this case p = 1.
a = 1/(4p) or 1/(4*1) or 1/4
write the equation in vertex form
y = a(x-h)^2 + k
y = 1/4(x-8)^2 -7
B. It would be 5/2 and -3/4.
