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3 years ago

7

A computer technician charges a fee of $75 for consultation plus $35 per hour. How much would your bill be if the technician wor

ked for 4.5 hours.
A.$90.75
B.$215.00
C.$372.50
D.$232.50

1 answer:

Travka [436]3 years ago

3 0

The answer is D-232.50

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What is the value of the expression 1 – r – a when r = 20 and a = 6?

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B. -25, because 1 minus 20 is -19, then you subtract 6 from -19, then the answer is -25.

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The exponential decay function A = A0(1/2)^t/P can be used to determine the amount A, of a radioactive substance present at time

amid [387]

Answer:

The half-life of the substance is about 288 days.

Step-by-step explanation:

The exponential decay function:

$\displaystyle A=A_0\left(\frac{1}{2}\right)^{t/P}$

Can determine the amount <em>A</em> of a radioactive substance present at time <em>t. A₀ </em>represents the initial amount and <em>P</em> is the half-life of the substance.

We are given that a substance loses 70% of its radioactivity in 500 days, and we want to determine the period of the half-life.

In other words, we want to determine <em>P. </em>

Since the substance has lost 70% of its radioactivity, it will have only 30% of its original amount. This occured in 500 days. Therefore, <em>A</em> = 0.3<em>A₀</em> when <em>t</em> = 500 (days). Substitute:

$\displaystyle 0.3A_0=A_0\left(\frac{1}{2}\right)^{500/P}$

Divide both sides by <em>A₀:</em>

$\displaystyle 0.3=\left(\frac{1}{2}\right)^{500/P}$

We can take the natural log of both sides:

$\displaystyle \ln(0.3)=\ln\left(\left(\frac{1}{2}\right)^{500/P}\right)$

Using logarithmic properties:

$\displaystyle \ln(0.3)=\frac{500}{P}\left(\ln\left(\frac{1}{2}\right)\right)$

So:

$\displaystyle \frac{500}{P}=\frac{\ln(0.3)}{\ln(0.5)}$

Take the reciprocal of both sides:

$\displaystyle \frac{P}{500}=\displaystyle \frac{\ln(0.5)}{\ln(0.3)}$

Use a calculator:

$\displaystyle P=\frac{500\ln(0.5)}{\ln(0.3)}\approx287.86$

The half-life of the substance is about 288 days.

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3 years ago

Use the binomial squares pattern to multiply (7c²+6)²

SashulF [63]

The solution is $49 c^{4}+84 c^{2}+36$

Explanation:

The expression is $\left(7 c^{2}+6\right)^{2}$

The square of a binomial is always a trinomial.

To determine the square of a binomial we shall use the formula.

The formula to find the square of a binomial is

$(a+b)^{2}=a^{2}+2 a b+b^{2}$

Let us use this formula to multiply the expression $\left(7 c^{2}+6\right)^{2}$

Here $a=7c^{2}$ and $b=6$

Substituting the values in the formula, we get,

$\left(7 c^{2}+6\right)^{2}=\left(7 c^{2}\right)^{2}+2 \cdot 7 c^{2} \cdot 6+6^{2}$

Squaring each term, we have,

$\left(7 c^{2}+6\right)^{2}=49 c^{4}+2\cdot 7 c^{2} \cdot 6+36$

Multiplying the product of two terms, we get,

$\left(7 c^{2}+6\right)^{2}=49 c^{4}+84c^{2}+36$

Thus, the solution is $49 c^{4}+84 c^{2}+36$

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Maya counts 55 passengers on the bus. There were only 50 passengers on the bus. What is Maya's percent error?

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Answer:

I don't know.

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Someone plzzzzzzz help me I don’t understand! Online school is hard and plzz help me I’ll give brianliest

Phoenix [80]

Answer:

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Step-by-step explanation:

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