Answer:

Try to solve the similtanious equation to find the first term and the common difference, then use that information to figure out the 80th term... Update me if you need further help ...
Answer:
16.2
Step-by-step explanation:
The angle internal to the triangle at B is the supplement of the one shown, so is 65°. That is equal to the angle internal to the triangle at D. Since the vertical angles at C are congruent, the two triangles are similar by the AA theorem.
Corresponding sides of similar triangles are proportional, so we can write the proportion shown in the attachment:
BC/FC = DC/AC
BC = FC(DC/AC) = 21.6(7.2/9.6)
BC = 16.2 . . . . matches the first choice
< ABC is a straight angle
no right angles
no complimentary angles
< ABD and < DBC are supplementary angles
To find the vertex of the parabola, we need to write it in a vertex form.
y=x² - 8x +12
1) complete the square
y=
x² - 8x +12
y =
x² -2*4x + 4² - 4² +12
y=
(x-4)² -16 +12
2) calculate and write a vertex
y=
(x-4)² -16 +12
y=
(x-4)² - 4
(x-4) ----- x- coordinate of the vertex x=4
y=(x-4)²
- 4 -------y- coordinate of the vertex y = - 4 Vertex is (4, -4).
Answer is (4, -4). No correct answer is given in choices.