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klasskru [66]
3 years ago
9

use number sense Duane and Mick are saving their money to build a tree house.Duane adds $5. ti their piggy bank every other week

Mick adds $2.every week.So far they have saved $45.How many weeks have they been saving money?
Mathematics
2 answers:
igor_vitrenko [27]3 years ago
6 0
5 weeks
Work: (9×5=45
5+2}
2. }these 5+2+2=9
5+2
2
5+2
2
5+2
2
5+2
2
Diano4ka-milaya [45]3 years ago
3 0
Duane and Mick have been saving money for 10 weeks.

Work

W1 5+2=7
W2 0+2=2
W3 5+2=7
W4 0+2= 2
Total so far is 18
W5 5+2 = 7
W6 0+2 = 2
W7 5+2 = 7
W8 0+2 = 2
Total now is 36
W9 5+2 = 7
W10 0+2 = 2
You end at 45!
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Write the complex numbers in standard form: 5/ 8-i
dedylja [7]

Answer:

a+bi

\frac{8}{13}  +  \frac{i}{13}

5 0
3 years ago
Can somebody explain how these would be done? The selected answer is incorrect, and I was told "Nice try...express the product b
trapecia [35]

Answer:

Solution ( Second Attachment ) : - 2.017 + 0.656i

Solution ( First Attachment ) : 16.140 - 5.244i

Step-by-step explanation:

Second Attachment : The quotient of the two expressions would be the following,

6\left[\cos \left(\frac{2\pi }{5}\right)+i\sin \left(\frac{2\pi \:}{5}\right)\right] ÷ 2\sqrt{2}\left[\cos \left(\frac{-\pi }{2}\right)+i\sin \left(\frac{-\pi \:}{2}\right)\right]

So if we want to determine this expression in standard complex form, we can first convert it into trigonometric form, then apply trivial identities. Either that, or we can straight away apply the following identities and substitute,

( 1 ) cos(x) = sin(π / 2 - x)

( 2 ) sin(x) = cos(π / 2 - x)

If cos(x) = sin(π / 2 - x), then cos(2π / 5) = sin(π / 2 - 2π / 5) = sin(π / 10). Respectively sin(2π / 5) = cos(π / 2 - 2π / 5) = cos(π / 10). Let's simplify sin(π / 10) and cos(π / 10) with two more identities,

( 1 ) \cos \left(\frac{x}{2}\right)=\sqrt{\frac{1+\cos \left(x\right)}{2}}

( 2 ) \sin \left(\frac{x}{2}\right)=\sqrt{\frac{1-\cos \left(x\right)}{2}}

These two identities makes sin(π / 10) = \frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}, and cos(π / 10) = \frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}.

Therefore cos(2π / 5) = \frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}, and sin(2π / 5) = \frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}. Substitute,

6\left[ \left\frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}+i\left\frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}\right] ÷ 2\sqrt{2}\left[\cos \left(\frac{-\pi }{2}\right)+i\sin \left(\frac{-\pi \:}{2}\right)\right]

Remember that cos(- π / 2) = 0, and sin(- π / 2) = - 1. Substituting those values,

6\left[ \left\frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}+i\left\frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}\right] ÷ 2\sqrt{2}\left[0-i\right]

And now simplify this expression to receive our answer,

6\left[ \left\frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}+i\left\frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}\right] ÷ 2\sqrt{2}\left[0-i\right] = -\frac{3\sqrt{5+\sqrt{5}}}{4}+\frac{3\sqrt{3-\sqrt{5}}}{4}i,

-\frac{3\sqrt{5+\sqrt{5}}}{4} = -2.01749\dots and \:\frac{3\sqrt{3-\sqrt{5}}}{4} = 0.65552\dots

= -2.01749+0.65552i

As you can see our solution is option c. - 2.01749 was rounded to - 2.017, and 0.65552 was rounded to 0.656.

________________________________________

First Attachment : We know from the previous problem that cos(2π / 5) = \frac{\sqrt{2}\sqrt{3-\sqrt{5}}}{4}, sin(2π / 5) = \frac{\sqrt{2}\sqrt{5+\sqrt{5}}}{4}, cos(- π / 2) = 0, and sin(- π / 2) = - 1. Substituting we receive a simplified expression,

6\sqrt{5+\sqrt{5}}-6i\sqrt{3-\sqrt{5}}

We know that 6\sqrt{5+\sqrt{5}} = 16.13996\dots and -\:6\sqrt{3-\sqrt{5}} = -5.24419\dots . Therefore,

Solution : 16.13996 - 5.24419i

Which rounds to about option b.

7 0
3 years ago
Help on this please.
dem82 [27]

Answer:

x = 46°

Step-by-step explanation:

the opposite angles of a cyclic quadrilateral are supplementary, sum to 180° , then

x + 134° = 180° ( subtract 134° from both sides )

x = 46°

8 0
2 years ago
Josh is hiking glacier national park. He has now hiked a total of 17km and is 2km short of being 1/2 of the way done with his hi
Alla [95]

Answer: The total length in kilometers is 38 km


Step-by-step explanation:


17 + 2 = 19 km is 1/2 of the total length, that is,


19 = (1/2)h


(1/2)h = 19 multiply both sides by 2


h = 2*19


h = 38 km

5 0
3 years ago
.48 ÷ 9.23 round to nearest tenth
Arisa [49]
The correct answer is
.05
3 0
3 years ago
Read 2 more answers
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