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1 year ago

7+4x= -5 helppppppppppppp

Mathematics

2 answers:

bekas [8.4K]1 year ago

8 0

Answer:

-3

Step-by-step explanation:

because if you subtract 7 from both side you get 4x=-12 then divide both sides by 4 and you get x=-3

Zepler [3.9K]1 year ago

7 0

X=-3

7+4x=-5
-7 -7
4x=-12
/4. 4/
X=-3

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Jason went to the post office and bought both 41-cent stamps and 26-cent postcards and spent $10.28. The number of stamps was 4

Charra [1.4K]

<h3>Jason bought 20 stamps of $0.41 each and 8 postcards of $0.26 each.</h3>

<em><u>Solution:</u></em>

Let stamps be s and postcards be p

Given that,

The number of stamps was 4 more than twice the number of postcards

s = 4 + 2p -------- eqn 1

Jason bought both 41-cent stamps and 26-cent postcards and spent $10.28

41 cent = $ 0.41

26 cent = $ 0.26

Therefore,

$s \times 0.41 + p \times 0.26 = 10.28$

0.41s + 0.26p = 10.28 --------- eqn 2

Substitute eqn 1 in eqn 2

0.41(4 + 2p) + 0.26p = 10.28

1.64 + 0.82p + 0.26p = 10.28

1.08p = 10.28 - 1.64

1.08p = 8.64

Divide both sides by 1.08

p = 8

Substitute p = 8 in eqn 1

s = 4 + 2(8)

s = 4 + 16

s = 20

Thus Jason bought 20 stamps and 8 post cards

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3 years ago

Use the quadratic formula to determine the exact solutions to the equation.

3241004551 [841]

Answer:

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3 years ago

Frank has a student loan of $55,780.

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Answer: $6197.77 would be the right answer

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3 years ago

How to write 10.4 as a mixed number in simplest form?

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3 years ago

Please Help!!<br><br>Use Euler’s formula to write in exponential form.

LekaFEV [45]

Answer:

C, $4e^{i(7\pi/4)}$

Step-by-step explanation:

To remind you, Euler's formula gives a link between trigonometric and exponential functions in a very profound way:

$e^{ix}=\cos{x}+i\sin{x}$

Given the complex number $2\sqrt{2}-2i\sqrt{2}$ , we want to try to get it in the same form as the right side of Euler's formula. As things are, though, we're unable to, and the reason for that has to do with the fact that both the sine and cosine functions are bound between the values 1 and -1, and 2√2 and -2√2 both lie outside that range.

One thing we could try would be to factor out a 2 to reduce both of those terms, giving us the expression $2(\sqrt{2}-i\sqrt{2})$

Still no good. √2 and -√2 are still greater than 1 and less than -1 respectively, so we'll have to reduce them a little more. With some clever thinking, you could factor out another 2, giving us the expression $4\left(\frac{\sqrt{2}}{2} -i\frac{\sqrt{2}}{2}\right)$ , and <em>now </em>we have something to work with.

Looking back at Euler's formula $e^{ix}=\cos{x}+i\sin{x}$ , we can map our expression inside the parentheses to the one on the right side of the formula, giving us $\cos{x}=\frac{\sqrt2}{2}$ and $\sin{x}=-\frac{\sqrt2}{2}$ , or equivalently:

$\cos^{-1}{\frac{\sqrt2}{2} }=\sin^{-1}-\frac{\sqrt2}{2} =x$

At this point, we can look at the unit circle (attached) to see the angle satisfying these two values for sine and cosine is 7π/4, so $x=\frac{7\pi}{4}$ , and we can finally replace our expression in parentheses with its exponential equivalent:

$4\left(\frac{\sqrt2}{2}-i\frac{\sqrt2}{2}\right)=4e^{i(7\pi/4)}$

Which is c on the multiple choice section.

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3 years ago