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3 years ago

2.0 hours and travels 5.0 km what's the average of speed?

Mathematics

1 answer:

disa [49]3 years ago

7 0

Average speed = 5/2 = 2.5 km/h

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Simplify the complex numbers using de Moivre's Theorem and match them with their solutions.

alexandr1967 [171]

For the numbers in $a+bi$ form, convert to polar form:

$1+i=\sqrt2\dfrac{1+i}{\sqrt2}=\sqrt2\left(\cos\dfrac\pi4+i\sin\dfrac\pi4\right)$

By DeMoivre's theorem,

$(1+i)^5=(\sqrt2)^5\left(\cos\dfrac{5\pi}4+i\sin\dfrac{5\pi}4\right)=4\sqrt2\dfrac{-1-i}{\sqrt2}=-4-4i$

$-1+i=\sqrt2\dfrac{-1+i}{\sqrt2}=\sqrt2\left(\cos\dfrac{3\pi}4+i\sin\dfrac{3\pi}4}\right)$

$\implies(-1+i)^6=(\sqrt2)^6\left(\cos\dfrac{18\pi}4+i\sin\dfrac{18\pi}4\right)=8i$

$\sqrt3+i=2\dfrac{\sqrt3+i}2=2\left(\cos\dfrac\pi6+i\sin\dfrac\pi6\right)$

$\implies2(\sqrt3+i)^{10}=2^{11}\left(\cos\dfrac{10\pi}6+i\sin\dfrac{10\pi}6\right)=2^{11}\dfrac{1-i\sqrt3}2=2^{10}(1-i\sqrt3)$

For the numbers already in polar form, DeMoivre's theorem can be applied directly:

$2\left(\cos20^\circ+i\sin20^\circ\right)^3=2\left(\cos60^\circ+i\sin60^\circ\right)=2\dfrac{1+i\sqrt3}2=1+i\sqrt3$

$2\left(\cos\dfrac\pi4+i\sin\dfrac\pi4\right)^4=2(\cos\pi+i\sin\pi)=-2$

At second glance, I think the 2s in the last two numbers should also be getting raised to the 3rd and 4th powers:

$\left(2(\cos20^\circ+i\sin20^\circ)\right)^3=8\left(\cos60^\circ+i\sin60^\circ\right)=4+4\sqrt3$

$\left(2\left(\cos\dfrac\pi4+i\sin\dfrac\pi4\right)\right)^4=16(\cos\pi+i\sin\pi)=-16$

4 0

3 years ago

CosA/secA+sinA/cosecA=1

Alona [7]

Step-by-step explanation:

please mark me as brainlest

4 0

2 years ago

7. Use graph paper to graph each linear function:<br> f(x) = 4x - 7

skelet666 [1.2K]

Any line can be graphed using two points. Select two x x values, and plug them into the equation to find the corresponding y y values. Any line can be graphed using two points. Select two x x values, and plug them into the equation to find the corresponding y y values.

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2 years ago

A store sells small notebooks for $6 and large notebooks for $10. If a student buys 6 notebooks and spends $52, how many of

NISA [10]

Answer:

you can say he bought 2 small notebooks and 4 big notebooks

Step-by-step explanation:

we have 52 dollars here

so if we have 4 large notebooks that will cost 40 dollars and if we have 2 small notebooks on addiction to that, that will cost 12 more dollars

now adding up 40 and 12 we get $52 !

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3 years ago