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3 years ago

Expand and simplify (x - 2)(- 1)

Mathematics

1 answer:

scZoUnD [109]3 years ago

7 0

Answer:

-x+2 or 2-x

Step-by-step explanation:

（x-2）（-1）

-x+2 or 2-x

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Solve equation, check for extraneous solutions

fiasKO [112]

Start with

$1=\dfrac{1}{n^2}+\dfrac{n^2-4n-5}{3n^2}$

We observe that both fractions are not defined if $n=0$ . So, we will assume $n \neq 0$ .

We multiply both numerator and denominator of the first fraction by 3 and we sum the two fractions:

$1=\dfrac{3}{3n^2}+\dfrac{n^2-4n-5}{3n^2} = \dfrac{n^2-4n-2}{3n^2}$

We multiply both sides by $3n^2$ :

$n^2-4n-2=3n^2$

We move everything to one side and solve the quadratic equation:

$2n^2+4n+2=0 \iff 2(n^2+2n+1)=0 \iff 2(n+1)^2=0 \iff n+1=0 \iff n=-1$

We check the solution:

$1=\dfrac{1}{1}+\dfrac{1+4-5}{3} \iff 1 = 1+0$

which is true

8 0

3 years ago

Evaluate Dx / ^ 9-8x - x2^

Solnce55 [7]

It depends on what you mean by the delimiting carats "^"...

Since you use parentheses appropriately in the answer choices, I'm going to go out on a limb here and assume something like "^x^" stands for $\sqrt x$ .

In that case, you want to find the antiderivative,

$\displaystyle\int\frac{\mathrm dx}{\sqrt{9-8x-x^2}}$

Complete the square in the denominator:

$9-8x-x^2=25-(16+8x+x^2)=5^2-(x+4)^2$

Now substitute $x+4=5\sin y$ , so that $\mathrm dx=5\cos y\,\mathrm dy$ . Then

$\displaystyle\int\frac{\mathrm dx}{\sqrt{9-8x-x^2}}=\int\frac{5\cos y}{\sqrt{5^2-(5\sin y)^2}}\,\mathrm dy$

which simplifies to

$\displaystyle\int\frac{5\cos 
y}{5\sqrt{1-\sin^2y}}\,\mathrm dy=\int\frac{\cos y}{\sqrt{\cos^2y}}\,\mathrm dy$

Now, recall that $\sqrt{x^2}=|x|$ . But we want the substitution we made to be reversible, so that

$x+4=5\sin y\iff y=\sin^{-1}\left(\dfrac{x+4}5\right)$

which implies that $-\dfrac\pi2\le y\le\dfrac\pi2$ . (This is the range of the inverse sine function.)

Under these conditions, we have $\cos y\ge0$ , which lets us reduce $\sqrt{\cos^2y}=|\cos y|=\cos y$ . Finally,

$\displaystyle\int\frac{\cos y}{\cos y}\,\mathrm dy=\int\mathrm dy=y+C$

and back-substituting to get this in terms of $x$ yields

$\displaystyle\int\frac{\mathrm dx}{\sqrt{9-8x-x^2}}=\sin^{-1}\left(\frac{x+4}5\right)+C$

4 0

3 years ago

A volunteer has 12 pounds of birdseed to put in the bird feeders in all of the city parks. There are 13/4 cups of birdseed in a

kozerog [31]

Answer:

$\large \boxed{28}$

Step-by-step explanation:

1. Calculate the number of cups

$\text{Cups} = \text{12 lb}\times\dfrac{1\frac{3}{4} \text{ cups}}{\text{1 lb}} =12\times\dfrac{\text{7 cups}}{4} = 3\times7\text{ cups}= \text{21 cups}$

2. Calculate the number of bird feeders

$\text{ Feeders}= \text{21 cups} \times \dfrac{\text{1 feeder}}{\frac{3}{4}\text{ cup}}=\text{21 cups} \times \dfrac{\text{4 feeders}}{\text{3 cups}} = 7 \times \text{ 4 feeders}\\\\= \textbf{28 feeders}\\\text{The volunteer can fill $\large \boxed{\textbf{28 feeders}}$}$

5 0

3 years ago

Which of the following expressions are equivalent? Justify your reasoning.. . a.4√x3. . 1. x−1. . b.10√x5•x4•x2. . c.x. 1. 3. •x

sladkih [1.3K]

A ) $\sqrt[4]{ x^{3} } = x^{3/4}$
B ) $\frac{1}{ x^{-1} } = x$
C ) $\sqrt[10]{ x^{5} * x^{4}* x^{2} } = \sqrt[10]{ x^{11} }= x^{11/10}$
D ) $x^{1/3} * x^{1/3} * x^{1/3} = x$
Therefore: B = D

7 0

3 years ago

Above is a graph of a proportional relationship. Explain the significance of the following points on this line:

KonstantinChe [14]

Answer:

1. at 1 hour, 3 miles is the distance.

2. at 0 hours, 0 miles is the distance.

3. at 3 hours, 9 miles is the distance.

5 0

3 years ago