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just olya [345]

3 years ago

7

Pls help ASAP

1 answer:

kondaur [170]3 years ago

3 0

Answer:

10 ml of a 72% solution, 20 ml of a 54% solution

Step-by-step explanation:

x ml - amount of a 72% solution

y ml - amount of a 54% solution

$\left \{ {{x+y=30} \atop {72x+54y=30*60}} \right.$

$\left \{ {{x=30-y} \atop {72(30-y)+54y=1800}} \right.$ (1)

(1) 2160-72y+54y=1800

y=20

x=30-y=30-20=10

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Find an equation of the plane with the given characteristics. The plane passes through the points (4, 3, 1) and (4, 1, -7) and i

Minchanka [31]

Answer:

$3x - 4y + z = 1$

Step-by-step explanation:

Given

$Point\ 1 = (4,3,1)$

$Point\ 2 = (4,1,-7)$

Perpendicular to $8x + 7y + 4z = 18$

Required

Determine the plane equation

The general equation of a plane is:

$a(x-x_1) + b(y - y_1) + c(z-z_1) = 0$

For $n =$

$(x_1,y_1,z_1) = (4,3,1)$

$(x_2,y_2,z_2) = (4,1,-7)$

First, we need to determine parallel vector $V_1$

$V_1 =$

$V_1 =$

$V_1 =$

$V_1$ is parallel to the required plane

From the question, the required plane is perpendicular to $8x + 7y + 4z = 18$

Next, we determine vector $V_2$

$V_2 =$

This implies that the required plane is parallel to $V_2$

Hence: $V_1$ and $V_2$ are parallel.

So, we can calculate the cross product $V_1 * V_2$

$V_1 =$

$V_2 =$

$n = V_1 * V_2$

$V_1 * V_2 =\left[\begin{array}{ccc}i&j&k\\0&2&8\\8&7&4\end{array}\right]$

The product is always of the form + - +

So:

$V_1 * V_2 = i\left[\begin{array}{cc}2&8\\7&4\end{array}\right]$ $-j\left[\begin{array}{cc}0&8\\8&4\end{array}\right]$ $+k\left[\begin{array}{cc}0&2\\8&7\end{array}\right]$

Calculate the product

$V_1 * V_2 = i(2*4- 8*7) - j(0*4- 8*8) + k(0*7 - 2 * 8)$

$V_1 * V_2 = i(8- 56) - j(0- 64) + k(0 - 16)$

$V_1 * V_2 = i(-48) - j(- 64) + k(- 16)$

$V_1 * V_2 = -48i +64j - 16k$

So, the resulting vector, n is:

$n =$

Recall that:

$n =$

By comparison:

$a = -48$ $b = 64$ $c = -16$

Substitute these values in $a(x-x_1) + b(y - y_1) + c(z-z_1) = 0$

$-48(x-x_1) + 64(y - y_1) -16(z-z_1) =0$

Recall that: $(x_1,y_1,z_1) = (4,3,1)$

So, we have:

$-48(x-4) + 64(y - 3) -16(z-1) =0$

$-48x + 192 + 64y -192 - 16z +16 = 0$

Collect Like Terms

$-48x + 64y - 16z = 0 - 192 + 192 - 16$

$-48x + 64y - 16z = -16$

Divide through by -16

$3x - 4y + z = 1$

<em>Hence, the equation of the plane is</em> $3x - 4y + z = 1$ <em></em>

4 0

3 years ago

If the interest is compounded continuously, what interest rate do you need for a 5000 investment to double in 10 years

velikii [3]

Answer:

rate = natural log (Total / Principal) / Years

We need 5,000 to become 10,000 in 10 years so,

rate = natural log (Total / Principal) / Years

rate = natural log(10,000 / 5,000) / 10

rate = natural log(2) / 10

rate = 0.69314718056 / 10

rate = .069314718056 which equals

rate = 6.9314718056 per cent

Source: https://www.1728.org/rate2.htm

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Step-by-step explanation:

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3 years ago

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Answer:

288

Step-by-step explanation:

the formula is 2(lw+wh+hl)

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width - 8

height 5

substitute the values and you get

2(64+40+40)

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