I think the answer is x equals 21
The percentage of this plane that's enclosed by the pentagons is closest to: D. 56.
<h3>How to determine the percentage?</h3>
Since the side of the small square is a, then the area of the tile is
given by:
Area of tiles = 9a²
<u>Note:</u> With an area of 9a², 4a² is covered by squares while 5a² by pentagons.
This ultimately implies that, 5/9 of the tiles are covered by pentagons and this can be expressed as a percentage as follows:
Percent = 5/9 × 100
Percent = 0.555 × 100
Percent = 55.5 ≈ 56%.
Read more on area of square here: brainly.com/question/8902873
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Complete Question:
The plane is tiled by congruent squares of side length a and congruent pentagons of side lengths a and a²/a, as arranged in the diagram below. The percent of the plane that is enclosed by the pentagons is closest to (A) 50 (B) 52 (C) 54 (D) 56 (E) 58
Answer:
1
+6
x
+
12
x
2
+
8x
3
Explanation:
We must use our knowledge of the binomial expansion:
Method 1:
We can use:
(
x
+
1
)
n
=
1
+
n
x
+
n
(
n
−
1
)
2
!
x
2
+
n
(
n
−
1
)
(
n
−
2
)
3
!
x
3
+
...
Substituting
n
=
3
and
x
for
2
x
⇒
(
2
x
+
1
)
3
=
1
+
(
3
⋅
2
x
)
+
3
⋅
2
2
!
⋅
(
2
x
)
2
+
3
⋅
2
⋅
1
3
!
⋅
(
2
x
)
3
=
1
+
6
x
+
12
x
2
+
8
x
3
Method 2:
We can use:
(
A
+
B
)
n
=
A
n
+
(
n
1
)
A
n
−
1
B
1
+
(
n
2
)
A
n
−
2
B
2
+
...
Letting
A
=
2
x
and
B
=
1
for this circumstance:
(
2
x
+
1
)
3
=
(
2
x
)
3
+
(
3
1
)
(
2
x
)
2
(
1
)
+
(
3
2
)
(
2
x
)
1
(
1
)
2
+
(
3
3
)
(
2
x
)
0
(
1
)
3
=
8
x
3
+
12
x
2
+
6
x
+
1
Step-by-step explanation: