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4 years ago

HELP PLEASE 100 POINTS WILL MARK BRAINLIEST

Mathematics

2 answers:

Sedbober [7]4 years ago

6 0

Answer:

the answer is C.

~batmans wife dun dun dun.....

sweet-ann [11.9K]4 years ago

3 0

Substitution is where you solve for one of the variables and then plug that in for the same variable in the other equation. Here, there is already an equation that is solved for a variable, $\sf y=4x-11$ . So we can plug in '4x - 11' for 'y' in the other equation:

$\sf 3x+5y=-9$

$\sf 3x+5(4x-11)=-9$

Distribute 5 into the parenthesis(multiply it to every term in the parenthesis):

$\boxed{\sf 3x+20x-55=-9}$

Your answer is C.

You might be interested in

X divided by 7 - 5 = 2 x/7 - 5 = 2

Black_prince [1.1K]

Answer:

x=4

Step-by-step explanation:

Multiply by 2 from both sides of equation.

2x/7-5=2*2

Simplify, to find the answer.

2*2=4

x=4 is the correct answer.

I hope this helps you, and have a wonderful day!

4 0

3 years ago

The manager of a warehouse would like to know how many errors are made when a product's serial number is read by a bar-code read

Bond [772]

Answer:

$(a)\ \bar x =20.5$

$(b)\ \sigma = 14.54$

Step-by-step explanation:

Given

$x: 36, 14, 21, 39, 11, 2$

Solving (a): The mean of the 6 samples.

This is calculated as:

$\bar x = \frac{\sum x}{n}$

So, we have:

$\bar x =\frac{36+ 14+ 21+ 39+ 11+ 2}{6}$

$\bar x =\frac{123}{6}$

$\bar x =20.5$

Solving (b): The sample standard deviation.

This is calculated using:

$\sigma = \sqrt{\frac{\sum(x - \bar x)^2}{n-1}}$

So, we have:

$\sigma = \sqrt{\frac{(36 - 20.5)^2 + (14 - 20.5)^2 + (21 - 20.5)^2 + (39 - 20.5)^2 + (11 - 20.5)^2 + (2 - 20.5)^2}{6-1}}$

$\sigma = \sqrt{\frac{1057.5}{5}}$

$\sigma = \sqrt{211.5}$

$\sigma = 14.54$

7 0

3 years ago

Can anyone explain those marked steps in case (iii)

Tema [17]

$\cos\dfrac{3x}2=\cos\left(\dfrac\pi2+\dfrac x2\right)$
$\implies \dfrac{3x}2=2n\pi+\dfrac\pi2+\dfrac x2$

follows from the fact that the cosine function is $2\pi$ -periodic, which means $\cos x=\cos(2\pi+x)$ . Roughly speaking, this is the same as saying that a point on a circle is the same as the point you get by completing a full revolution around the circle (i.e. add $2\pi$ to the original point's angle with respect to the horizontal axis).

If you make another complete revolution (so we're effectively adding $4\pi$ ) we get the same result: $\cos x=\cos(4\pi+x)$ . This is true for any number of complete revolutions, so that this pattern holds for any even multiple of $\pi$ added to the argument. Therefore $\cos x=\cos(2n\pi+x)$ for any integer $n$ .

Next, because $\cos(-x)=\cos x$ , it follows that $\cos x=\cos(2n\pi-x)$ is also true for any integer $n$ . So we have

$\implies \dfrac{3x}2=2n\pi\pm\left(\dfrac\pi2+\dfrac x2\right)$

The rest follows from considering either case and solving for $x$ .