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Hoochie [10]
3 years ago
8

Solve the system by substitution.

Mathematics
1 answer:
tino4ka555 [31]3 years ago
3 0
As we know y=3/4x-3
Let's put it in the second equation
3/4x-3=1/4x+1
3/4 x -1/4 x = 1+3
2/4 x = 4
X= 4*4/2
x=8
Put x= 8 in first equation
y= 3/4 *8 -3
y=6-3
y=3
Check the answer
3=3/4 *8 -3
3=6-3
3=3
Correct
So(y, x) = (3,8)
Because x=8 and y=3
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A jeweler who buys a ring from a jewelry maker for $125 marked with the price by 135% for sale in the store what is the selling
siniylev [52]
Marked up by 135% means
new price=original price+(original price times markup) =125+(125 times 1.35)=293.75
tax
293.75 times 0.075=22.03125

293.75-22.03125=271.718 so aprox $271.72


selling price would be $271.72
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3 years ago
Three consecutive integers have a sum of 42. find the integers.
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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

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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
Find the value of x in the triangle shown below
mezya [45]

Answer:

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Step-by-step explanation:

use the pythagorean theorem

3²+x²=6²

9+x²=36

x²=27

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x=√27

7 0
3 years ago
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