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3 years ago

Simplify (4ab^2)^3 Any help is appreciated

Mathematics

1 answer:

Pie3 years ago

3 0

Answer:

$64a^{3} b^{6}$

Step-by-step explanation:

1) Distribute the exponent outside of the parentheses to the terms inside the parentheses. In this case, multiply the 3 outside the parentheses with the exponent of each of the terms inside:

$(4ab^{2} )^3$

$4^{3}$ · $a^{3}$ · $b^{6}$

2) The variables are fine - you can't simplify them further. All you need to do now is multiply the $4^{3}$ out. Remember that it's kind of like asking, "what is 4 × 4 ×4?"

$4$ · $4$ · $4$ · $a^{3}$ · $b^{6}$

$16$ · $4$ · $a^{3}$ · $b^{6}$

$64a^{3} b^{6}$

Therefore, $64a^{3} b^{6}$ is the answer.

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Answer it pls and explain too

snow_tiger [21]

Answer:

y-intercept: (0, 5); slope: 1/4

Step-by-step explanation:

The slope (m) is found from ...

m = (y2 -y1)/(x2 -x1)

Using the first two points in the table, this is ...

m = (8 -6)/(12 -4) = 2/8 = 1/4 . . . . . eliminates choices A and C

Then, the point-slope form of the equation of the line can be written as ...

y -y1 = m(x -x1)

y -6 = (1/4)(x -4) . . . fill in known values

y = 1/4x -1 +6 . . . . . add 6

y = 1/4x +5

Then the value of y when x=0 is ...

y = 0 +5 = 5

So, the y-intercept is (0, 5) and the slope is 1/4, matching the last choice.

7 0

3 years ago

For the function defined by f(t)=2-t, 0≤t<1, sketch 3 periods and find:

Oksi-84 [34.3K]

The half-range sine series is the expansion for $f(t)$ with the assumption that $f(t)$ is considered to be an odd function over its full range, $-1$ . So for (a), you're essentially finding the full range expansion of the function

$f(t)=\begin{cases}2-t&\text{for }0\le t$

with period 2 so that $f(t)=f(t+2n)$ for $|t|$ and integers $n$ .

Now, since $f(t)$ is odd, there is no cosine series (you find the cosine series coefficients would vanish), leaving you with

$f(t)=\displaystyle\sum_{n\ge1}b_n\sin\frac{n\pi t}L$

where

$b_n=\displaystyle\frac2L\int_0^Lf(t)\sin\frac{n\pi t}L\,\mathrm dt$

In this case, $L=1$ , so

$b_n=\displaystyle2\int_0^1(2-t)\sin n\pi t\,\mathrm dt$
$b_n=\dfrac4{n\pi}-\dfrac{2\cos n\pi}{n\pi}-\dfrac{2\sin n\pi}{n^2\pi^2}$
$b_n=\dfrac{4-2(-1)^n}{n\pi}$

The half-range sine series expansion for $f(t)$ is then

$f(t)\sim\displaystyle\sum_{n\ge1}\frac{4-2(-1)^n}{n\pi}\sin n\pi t$

which can be further simplified by considering the even/odd cases of $n$ , but there's no need for that here.

The half-range cosine series is computed similarly, this time assuming $f(t)$ is even/symmetric across its full range. In other words, you are finding the full range series expansion for

$f(t)=\begin{cases}2-t&\text{for }0\le t$

Now the sine series expansion vanishes, leaving you with

$f(t)\sim\dfrac{a_0}2+\displaystyle\sum_{n\ge1}a_n\cos\frac{n\pi t}L$

where

$a_n=\displaystyle\frac2L\int_0^Lf(t)\cos\frac{n\pi t}L\,\mathrm dt$

for $n\ge0$ . Again, $L=1$ . You should find that

$a_0=\displaystyle2\int_0^1(2-t)\,\mathrm dt=3$

$a_n=\displaystyle2\int_0^1(2-t)\cos n\pi t\,\mathrm dt$
$a_n=\dfrac2{n^2\pi^2}-\dfrac{2\cos n\pi}{n^2\pi^2}+\dfrac{2\sin n\pi}{n\pi}$
$a_n=\dfrac{2-2(-1)^n}{n^2\pi^2}$

Here, splitting into even/odd cases actually reduces this further. Notice that when $n$ is even, the expression above simplifies to

$a_{n=2k}=\dfrac{2-2(-1)^{2k}}{(2k)^2\pi^2}=0$

while for odd $n$ , you have

$a_{n=2k-1}=\dfrac{2-2(-1)^{2k-1}}{(2k-1)^2\pi^2}=\dfrac4{(2k-1)^2\pi^2}$

So the half-range cosine series expansion would be

$f(t)\sim\dfrac32+\displaystyle\sum_{n\ge1}a_n\cos n\pi t$
$f(t)\sim\dfrac32+\displaystyle\sum_{k\ge1}a_{2k-1}\cos(2k-1)\pi t$
$f(t)\sim\dfrac32+\displaystyle\sum_{k\ge1}\frac4{(2k-1)^2\pi^2}\cos(2k-1)\pi t$

Attached are plots of the first few terms of each series overlaid onto plots of $f(t)$ . In the half-range sine series (right), I use $n=10$ terms, and in the half-range cosine series (left), I use $k=2$ or $n=2(2)-1=3$ terms. (It's a bit more difficult to distinguish $f(t)$ from the latter because the cosine series converges so much faster.)