PLEASE SOMEONE HELP ASAP

What value of m makes the system of linear equations mx − y + 3 = 0, (2m − 1)x − y + 4 = 0 have no solution?

Morgarella [4.7K]

Answer:

m ≠1 ( all m in R except 1 )

Step-by-step explanation:

hello :

mx − y + 3 = 0.....(*)

(2m − 1)x − y + 4 = 0 ....(**)

multiply (*) by : -1 you have : -mx+y-3=0 ....(***)

(2m − 1)x − y + 4 = 0 ....(**)

add(***) and(**) : -mx+ (2m − 1)x+1 =0

(2m-m-1)x+1=0

(m-1)x = -1

this system have no solution if : m-1≠0 means : m ≠1

6 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

Josh has a rewards card for a movie theater. He receives 15 points for becoming a rewards card holder. He earns 3.5 points for e

Savatey [412]

Answer:

C. 55 $\leq$ 3.5x + 15

Step-by-step explanation:

i found it on google

6 0

3 years ago

find the equation of a line that is parallel to the straight line 2x-y=-3 and crosses the x-axis at x=-5

Alecsey [184]

Answer:

y=2x+10

Step-by-step explanation:

In line equations its helpful to write your line in the form y = ax + b. This helps because a is always the gadient of the line and b is always the y intercept.

In this case it is y=2x+3

All parallel lines have the same gradient. The gradient of this line = 2.

If the line crosses the x axis at x=-5, then when x =-5 y = 0.

If you put all this in the form y =ax + b you get 0 = 2(-5) +b

So all you need to do to find b is rearrange. b = 10.

Therefore your line has gradient 2 and y intercept 10.

y = 2x + 10

7 0

3 years ago

Jilly has 8 pens. Three of the pens are purple. She will choose two pens to place in her school bag. What is the probability tha

Finger [1]

Answer:

3/8 is the probability

Step-by-step explanation:

3 0

3 years ago