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3 years ago

21.14,7.2,4.5 are these irrational or rational?

Mathematics

1 answer:

77julia77 [94]3 years ago

6 0

Answer:

Rational. They have termination decimals, so the next digit can be predicted. Therefore, those numbers are rational.

Step-by-step explanation:

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Plzz Answer<br> first to answer correctly will get brainliest

RoseWind [281]

Answer: 1/8

Step-by-step explanation:

Multiply by the reciprocal which would be 1/2, so 1/4x1/2 would be 1/8

3 0

3 years ago

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I am doing this test and I need questions questions ASAP I will give brainiest to whoever answers it correctly

Troyanec [42]

Answer:

The correct answer there is the first option

6 0

3 years ago

You have asked to design a rectangle box with a square base and an open top. The volume of the box must be620 cm to the 3rd powe

hammer [34]

Answer:

$69.21

Step-by-step explanation:

Since the box has a square base the length and breadth of the box will be equal. Let it be $x$

Let h be the height of the box

V = Volume of the box = $620\ \text{cm}^3$

$x^2h=620\\\Rightarrow h=\dfrac{620}{x^2}$

Now surface area of the box with an open top is given

$s=x^2+4xh\\\Rightarrow s=x^2+4x\dfrac{620}{x^2}\\\Rightarrow s=x^2+\dfrac{2480}{x}$

Differentiating with respect to x we get

$\dfrac{ds}{dx}=2x-\dfrac{2480}{x^2}$

Equating with zero

$0=2x-\dfrac{2480}{x^2}\\\Rightarrow 2x^3-2480=0\\\Rightarrow x^3=\dfrac{2480}{2}\\\Rightarrow x=(1240)^{\dfrac{1}{3}}\\\Rightarrow x=10.74$

Double derivative of the function

$\dfrac{d^2s}{ds^2}=2+\dfrac{4960}{x^3}=2+\dfrac{4960}{1240}\\\Rightarrow \dfrac{d^2s}{ds^2}=6>0$

So, x at 10.74 is the minimum value of the function.

$h=\dfrac{620}{x^2}\\\Rightarrow h=\dfrac{620}{10.74^2}\\\Rightarrow h=5.37$

So, minimum length and breadth of the box is 10.74 cm while the height of the box is 5.37 cm.

The total area of the sides is $4xh=4\times 10.74\times 5.37=230.7\ \text{cm}^2$

The area of the base is $x^2=10.74^2=115.35\ \text{cm}^2$

Cost of the base is $0.40 per square cm

Cost of the side is $0.10 per square cm

Minimum cost would be

$230.7\times 0.1+0.4\times 115.34=\$69.21$

The minimum cost of the box is 69.21 dollars.

8 0

3 years ago

If a number cube is rolled twice, what is the probability of rolling a 1 both times

Mila [183]

Answer:

$\frac{1}{12}$

Step-by-step explanation:

3 0

3 years ago

A metal bar weighs 9.25 ounces. 65% of the bar is gold. how many ounces of gold is in the bar?

Elza [17]

Not sure I'm right but:

If the bar weighs 9.25 ounces and 65% of the bar is gold, you'd do 65% of 9.25. So the answer would be <span>65% of 9.25= 6.0125</span>

6 0

4 years ago