Solve variable 3/4x-5=7

Drawing Conclusions

maksim [4K]

Answer:

Some of the Exponents = -2 that is true, not 2.

Step-by-step explanation:

Let's check one at a time.

(a)The 6 without an exponent is equivalent to the 6 having a 0 exponent.

$6^{0} =1$ and $6^{1}$ = 6 (no exponent. 6 $\neq$ 1 therefore this statement is False.

(b)The sum of the exponents is -2.

let's check , if the base is same we can add the exponents that is the exponent rule.(well established).

if we add exponents in the given expression we get.

$6^{1} 6^{0} 6^{3} =6^{1+0+(-3)} =6^{-2}$ , therefore we can see that the sum of the exponents = -2 this is true.

(c) An equivalent expression is 65.6-7, lets evaluate our above expression, it is equal to $\frac{1}{36}$ which we can see that $\frac{1}{36} \neq 65.6-7$ ,therefore this statement is false as well.

3 0

3 years ago

How to know if a function is periodic without graphing it ?

zhenek [66]

A function $f(t)$ is periodic if there is some constant $k$ such that $f(t+k)=f(k)$ for all $t$ in the domain of $f(t)$ . Then $k$ is the "period" of $f(t)$ .

Example:

If $f(x)=\sin x$ , then we have $\sin(x+2\pi)=\sin x\cos2\pi+\cos x\sin2\pi=\sin x$ , and so $\sin x$ is periodic with period $2\pi$ .

It gets a bit more complicated for a function like yours. We're looking for $k$ such that

$\pi\sin\left(\dfrac\pi2(t+k)\right)+1.8\cos\left(\dfrac{7\pi}5(t+k)\right)=\pi\sin\dfrac{\pi t}2+1.8\cos\dfrac{7\pi t}5$

Expanding on the left, you have

$\pi\sin\dfrac{\pi t}2\cos\dfrac{k\pi}2+\pi\cos\dfrac{\pi t}2\sin\dfrac{k\pi}2$

and

$1.8\cos\dfrac{7\pi t}5\cos\dfrac{7k\pi}5-1.8\sin\dfrac{7\pi t}5\sin\dfrac{7k\pi}5$

It follows that the following must be satisfied:

$\begin{cases}\cos\dfrac{k\pi}2=1\\\\\sin\dfrac{k\pi}2=0\\\\\cos\dfrac{7k\pi}5=1\\\\\sin\dfrac{7k\pi}5=0\end{cases}$

The first two equations are satisfied whenever $k\in\{0,\pm4,\pm8,\ldots\}$ , or more generally, when $k=4n$ and $n\in\mathbb Z$ (i.e. any multiple of 4).

The second two are satisfied whenever $k\in\left\{0,\pm\dfrac{10}7,\pm\dfrac{20}7,\ldots\right\}$ , and more generally when $k=\dfrac{10n}7$ with $n\in\mathbb Z$ (any multiple of 10/7).

It then follows that all four equations will be satisfied whenever the two sets above intersect. This happens when $k$ is any common multiple of 4 and 10/7. The least positive one would be 20, which means the period for your function is 20.

Let's verify:

$\sin\left(\dfrac\pi2(t+20)\right)=\sin\dfrac{\pi t}2\underbrace{\cos10\pi}_1+\cos\dfrac{\pi t}2\underbrace{\sin10\pi}_0=\sin\dfrac{\pi t}2$

$\cos\left(\dfrac{7\pi}5(t+20)\right)=\cos\dfrac{7\pi t}5\underbrace{\cos28\pi}_1-\sin\dfrac{7\pi t}5\underbrace{\sin28\pi}_0=\cos\dfrac{7\pi t}5$

More generally, it can be shown that

$f(t)=\displaystyle\sum_{i=1}^n(a_i\sin(b_it)+c_i\cos(d_it))$

is periodic with period $\mbox{lcm}(b_1,\ldots,b_n,d_1,\ldots,d_n)$ .

4 0

3 years ago

You decide to bake a cake for your sister's birthday, but you discover you don't have enough eggs. Before you go to the store, y

zheka24 [161]

Answer:

I think it will c because I have some eggs at home

5 0

3 years ago

Jackson’s mother buys 4 packs of hamburger meat.Each pack contains 4/6 of a pound of meat.How much total meat did she buy?

wariber [46]

Answer:

8/3 total or 2 2/3

Step-by-step explanation:

4 x 4/6 is the same thing as...

4/1 x 4/6

Multiply straight across...

16/6

Simplify...

8/3 total or 2 2/3

:)

5 0

2 years ago

Sam lives near a lagoon in the Caribbean that is populated by flamingos. Sam decides to figure out approximately how many flamin

klasskru [66]

Answer:

about 330

Step-by-step explanation:

280 rounded is 330 and 30 is already rounded so you would add 30 plus 330

5 0

3 years ago