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2 years ago

Find the vector, not with determinants, but by using properties of cross products. k × (i − 3j)

1 answer:

3 0

$\mathbf k\times(\mathbf i-3\mathbf j)=(\mathbf k\times\mathbf i)-3(\mathbf k\times\mathbf j)$
$=\mathbf j-3(-\mathbf i)$
$=3\mathbf i+\mathbf j$

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When three pipes fill a pool, they can finish in 12 hours. Two of the pipes can finish in 18 hours if they are working together.

Ymorist [56]

The number of pipes * the time is a constant proportional to the pool size.

3*12 = 2*18 = 1*36. So one pipe would take 36 hours.

6 0

2 years ago

PLEASE HELP MEE please33

Sever21 [200]

Answer:

x=3, y=-1

Step-by-step explanation:

$3x+y=8, 2x-2y=8$

Double the first equation, then add the second

6x+2y=16

+ 2x-2y=8

The y's cancel each other out.

8x=24

x=3

Solve for y

6-2y=8

2y=-2

y=-1

Double check:

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2 years ago

What is the expression in factored form?x^2+13x+14

nydimaria [60]

Answer:

$\left(x-\dfrac{-13+\sqrt{113}}{2}\right)\left(x-\dfrac{-13-\sqrt{113}}{2}\right).$

Step-by-step explanation:

To factor the expression $x^2+13x+14$ you need to know its roots.

First find the discriminant of this quadratic polynomial:

$D=13^2-4\cdot 1\cdot 14=169-56=113.$

Then the roots of the expression $x^2+13x+14$ are

$x_{1,2}=\dfrac{-13\pm \sqrt{113}}{2}.$

Now the factored form is

$\left(x-\dfrac{-13+\sqrt{113}}{2}\right)\left(x-\dfrac{-13-\sqrt{113}}{2}\right).$

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2 years ago

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mariarad [96]

Answer:

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Step-by-step explanation:

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2 years ago

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KatRina [158]

Answer:

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Step-by-step explanation:

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1 year ago

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