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4 years ago

NEED HELP ASAP!! Can someone explain how to do this

Mathematics

2 answers:

kati45 [8]4 years ago

8 0

Answer:

Step-by-step explanation:

I NEED THAT TOO

vladimir2022 [97]4 years ago

5 0

Answer:

10 degrees

Step-by-step explanation:

(5x(10))+3=53 degrees

(3x(10))+7=37 degrees

53+37=90 degrees

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WILL GIVE BRAINLIEST

galina1969 [7]

Answer:

x= 3 inches

Step-by-step explanation:

-The volume of a box is given by the formula:

$V=lwh\\\\l-length\\w-width\\h-height$

-We are given the dimensions h=x+2, l=2x+5 and w=4x-1.

We substitute this values in the formula and equate to the volume value.

$V=lwh\\\\605=(x+2)(2x+5)(4x-1)\\\\605=8x^3+34x^2+31x-10$

#We take the values to the same side and equate to zero;

$8x^3+34x^2+31x-615=0\\\\\\\#Factor\\\\\\(x-3)(8x^2+58x+205)=0$

#Applying the zero factor principal to obtain the different values of x:

$(x-3)=0\\\\\therefore x=3\ \ \ \ \ \ ...i\\\\(8x^2+58x+205)=0$

#We use the quadratic formula to solve the two other values of x:

$(8x^2+58x+205)=0\\x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\=\frac{-58\pm\sqrt{58^2-4\times 8\times 205}}{2\times 8}\\\\x=-3.625+3.533i \ and \ x=-3.625-3.533i$

The two other values are negatives. Ignore them since length cannot be a negative.

The only reasonable value of x is x=3

#We substitute in the formula to validate:

$V=lwh\\\\=(x+2)(2x+5)(4x-1)\\\\=(3+2)(2*3+5)(4*3-1)\\\\=605$

Hence, the value of x is 3 inches

7 0

3 years ago

A radioactive substance decays at a continuous rate of 17% per year, and 250 mg of the substance is present in the year 2009.

yaroslaw [1]

Answer:

a) $A(t) = 250 (1-0.17)^t = 250(0.83)^t$

b) $A(t=14) = 250 (0.83)^{14}= 18.408 mg$

c) For this case we want to find when the quantity is below 25 mg, so we can do this:

$25 = 250 (0.83)^t$

We can divide both sided by 250 and we got:

$0.1 = 0.83^t$

Now we can apply natural log on both sides and we got:

$ln(0.1) = t ln (0.83)$

And if we solve for t we got:

$t = \frac{ln(0.1)}{ln(0.83)}= 12.358 years$

So the answer for this case would be 12.358 years after.

Step-by-step explanation:

Part a

For this case we know that the decay rate per year is about 17% or 0.17 in fraction and the initial amount is 250 mg for 2009, we can define the model like this:

$A(t) = A_o (1-r)^t$

Where A represent the amount of the substance in mg, r the decay rate = 0.17 and t the number of years after 2009.

Our model for this case would be:

$A(t) = 250 (1-0.17)^t = 250(0.83)^t$

Part b

For this case we have that t= 2023-2009=14 years, so then we can find the amount of substance like this:

$A(t=14) = 250 (0.83)^{14}= 18.408 mg$

Part c

For this case we want to find when the quantity is below 25 mg, so we can do this:

$25 = 250 (0.83)^t$

We can divide both sided by 250 and we got:

$0.1 = 0.83^t$

Now we can apply natural log on both sides and we got:

$ln(0.1) = t ln (0.83)$

And if we solve for t we got:

$t = \frac{ln(0.1)}{ln(0.83)}= 12.358 years$

So the answer for this case would be 12.358 years after.

6 0

3 years ago

Solve this equation for x: x2 + 11x + 28 = 0

saw5 [17]

Answer:

Step-by-step explanation:

The answer is factor the trinomial

5 0

4 years ago

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(x-81/10)> (68-81/10) and (x-81/10)<(68-81/10)

Fofino [41]

Answer:

what you need should be testing for u

6 0

3 years ago

Another name for slope is the constant rate of change or speed.<br><br> True<br> False

marysya [2.9K]

Answer:true

Step-by-step explanation:

3 0

3 years ago

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