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3 years ago

NEED HELP QUICK! plz and thx

Mathematics

1 answer:

Drupady [299]3 years ago

4 0

Answer:

number3 and number 4

Step-by-step explanation:

A negative times or divided by a positive = a negative. Thats the rule.

So choose the answers that have a positive number in it's deniminator. Those would be 2 and 4.2

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Marvin is comparing two different music websites. Website A charges $10 per month for a subscription and $0.25 per song. Website

Alecsey [184]

Website A:
c = 10 + 0.25 s
where c is the cost and s is the number of songs.
Website B:
c = 0.75 s
The equation ( answer ):
10 + 0.25 s = 0.75 s
We can solve this equation:
10 = 0.5 s
s = 10 : 0.5
s = 20 ( Marvin would have to buy 20 songs to to make the costs equal )

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4 years ago

how do you determine if the answer to a problem is negative or positive in division multiplication addition and subtraction

erica [24]

In multiplication, a negative times a positive has a negative answer. if both are positive or both are negative, the answer is positive.
5 * -5 = -25
-5* -5 = 25

in divisions say you have
-5/5 = -1
-5/-5= 1
5/-5= -1

in addition and subtraction, subtracting a negative means to add the two numbers. adding a negative means to subtract the second number.

5+ (-5) = 0
5- (-5) = 10

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3 years ago

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tigry1 [53]

Answer:

The general equation of a circle is x2 + y2 - 6x - 16y + 48 = 0

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3 years ago

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3 years ago

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Find the integral using substitution or a formula.

Nadusha1986 [10]

$\rm \int \dfrac{x^2+7}{x^2+2x+5}~dx$

Derivative of the denominator:
$\rm (x^2+2x+5)'=2x+2$

Hmm our numerator is 2x+7. Ok this let's us know that a simple u-substitution is NOT going to work. But let's apply some clever Algebra to the numerator splitting it up into two separate fractions. Split the +7 into +2 and +5.

$\rm \int \dfrac{x^2+2+5}{x^2+2x+5}~dx$

and then split the fraction,

$\rm \int \dfrac{x^2+2}{x^2+2x+5}~dx+\int\dfrac{5}{x^2+2x+5}~dx$

Based on our previous test, we know that a simple substitution will work for the first integral: $\rm \quad u=x^2+2x+5\qquad\to\qquad du=2x+2~dx$

So the first integral changes,

$\rm \int \dfrac{1}{u}~du+\int\dfrac{5}{x^2+2x+5}~dx$

integrating to a log,

$\rm ln|x^2+2x+5|+\int\dfrac{5}{x^2+2x+5}~dx$

Other one is a little tricky. We'll need to complete the square on the denominator. After that it will look very similar to our arctangent integral so perhaps we can just match it up to the identity.

$\rm x^2+2x+5=(x^2+2x+1)+4=(x+1)^2+2^2$

So we have this going on,

$\rm ln|x^2+2x+5|+\int\dfrac{5}{(x+1)^2+2^2}~dx$

Let's factor the 5 out of the intergral,
and the 4 from the denominator,

$\rm ln|x^2+2x+5|+\frac54\int\dfrac{1}{\frac{(x+1)^2}{2^2}+1}~dx$

Bringing all that stuff together as a single square,

$\rm ln|x^2+2x+5|+\frac54\int\dfrac{1}{\left(\dfrac{x+1}{2}\right)^2+1}~dx$

Making the substitution: $\rm \quad u=\dfrac{x+1}{2}\qquad\to\qquad 2du=dx$

giving us,

$\rm ln|x^2+2x+5|+\frac54\int\dfrac{1}{\left(u\right)^2+1}~2du$

simplying a lil bit,

$\rm ln|x^2+2x+5|+\frac52\int\dfrac{1}{u^2+1}~du$

and hopefully from this point you recognize your arctangent integral,

$\rm ln|x^2+2x+5|+\frac52arctan(u)$

undo your substitution as a final step,
and include a constant of integration,

$\rm ln|x^2+2x+5|+\frac52arctan\left(\frac{x+1}{2}\right)+c$

Hope that helps!
Lemme know if any steps were too confusing.

8 0

3 years ago