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Luda [366]
3 years ago
7

A rectangle has a perimeter of 80 cm. If its width is x, express its length and area in terms of x, and find the maximum area.

Mathematics
1 answer:
Veseljchak [2.6K]3 years ago
7 0
Perimiter=2L+2W

w=x
P=80

80=2L+2x
diviide by 2
40=L+x

40-L=x
40-x=L


the area is found by legnth times width
LW or Lx
for a maximum area, try to get the legnths of the sides the same
therefor
L=W=x for max area
40=x+x
40=2x
divide 2
20=x
max area =legnth times width=20^2=400

note: all squares are rectangles, but not all rectangles are squares


L=40-x
A=(40-x)(x)

max area=400 cm^2

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3 years ago
An 8 oz glass of grape juice contains 0.6 mg of iron. About what percent of RDA of iron for an 15 year old male is provided by 8
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Answer:

5.45%


Step-by-step explanation:

To find info of a 15 year old male, you look at the Age Group of 14 - 18, beside Male.

The RDA of Iron is given as 11 mg

From a 8 oz glass of grape juice, he gets 0.6 mg.


<em>What percent is 0.6 mg of total 11 mg??</em>


Divide 0.6 by 11 and then multiply by 100 to get the answer. So we have:

\frac{0.6}{11}=0.0545*100=5.45

Thus, 5.45% of RDA of iron is provided by an 8 oz glass of grape juice.

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8 0
3 years ago
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Dhanraj spent $204.20 purchasing volleyballs and basketballs.
Lemur [1.5K]

Answer:

Number of volleyballs bought = 8

Number of basketballs bought = 11

Step-by-step explanation:

Given that:

Total amount spent = $204.20

Let,

x be the number of volleyballs

y be the number of basketballs

According to given statement;

y = x+3     Eqn 1

8.20x+12.60y=204.20     Eqn 2

Putting value of y from Eqn 1 in Eqn 2

8.20x + 12.60(x+3) = 204.20

8.20x + 12.60x + 37.80 = 204.20

20.80x = 204.20 - 37.80

20.80x = 166.40

Dividing both sides by 20.80

\frac{20.80x}{20.80}=\frac{166.40}{20.80}\\x=8

Putting x=8 in Eqn 1

y = 8+3 = 11

Hence,

Number of volleyballs bought = 8

Number of basketballs bought = 11

6 0
2 years ago
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