Answer:
Step-by-step explanation:
Because of the nature of the information we are given, we have no choice but to use the equation

and solve for a.
We know by the info that the vertex is (0, 84). We also know that if the vertex is at the origin, and that the base is 42 feet wide, it spans 21 feet to the right of the origin and 21 feet to the left of the origin. That means that we have 2 coordinates from which we need to pick one for our x and y in the equation. I don't like negatives, so I am going to choose the coordinate (21, 0) as x and y. Because this parabola opens upside down, as archways of door openings do, our "a" value better come out algebraically as a negative. Let's see...From the vertex we have that h = 0 and k = 84. So filling in:
and simplifying a bit:
0 = 441a + 84 and
-84 = 441a so
Good, a is negative. Your equation is, then:

Answer:
5/7
Step-by-step explanation:
first of mean to divide
so it really saying x ÷ 3/4 and x = 15/28
15/28 ÷ 3/4 but you cant divide fractions
so we use copy dote flip
copy 15/28
dote ×
flip 4/3
15/28 × 4/3
then cross simplafiy so 4 can go into 28, 7 rimes. and 3 can go into 15, 5 times
5/7
Answer:15
Step-by-step explanation:
If 85% pass then 15% failed and 15% of 1,200 is 180 so 180 people failed.
Answer:
The expressions which equivalent to
are:
⇒ B
⇒ C
Step-by-step explanation:
Let us revise some rules of exponent
Now let us find the equivalent expressions of 
A.
∵ 4 = 2 × 2
∴ 4 = 
∴
=
- By using the second rule above multiply 2 and (n + 2)
∵ 2(n + 2) = 2n + 4
∴
=
B.
∵ 4 = 2 × 2
∴ 4 = 2²
∴
= 2² ×
- By using the first rule rule add the exponents of 2
∵ 2 + n + 1 = n + 3
∴
=
C.
∵ 8 = 2 × 2 × 2
∴ 8 = 2³
∴
= 2³ ×
- By using the first rule rule add the exponents of 2
∵ 3 + n = n + 3
∴
=
D.
∵ 16 = 2 × 2 × 2 × 2
∴ 16 = 
∴
=
×
- By using the first rule rule add the exponents of 2
∵ 4 + n = n + 4
∴
=
E.
is in its simplest form
The expressions which equivalent to
are:
⇒ B
⇒ C
Answer:
Below!
Step-by-step explanation:
111.5