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Sonja [21]
3 years ago
13

One boat travelling 15 mph goes 47 miles downstream in the same amount of time that another boat going 20 mph goes 40 miles upst

ream. How fast is the current in mph? (Round your answer to the nearest tenth of miles per hour and enter only the numerical part
Mathematics
1 answer:
vazorg [7]3 years ago
6 0

Answer:

  3.9 mi/h

Step-by-step explanation:

We assume that the given speeds are the speeds of the boats relative to the water. If c is the speed of the current, we have ...

  time = distance/speed

  47/(15 +c) = 40/(20 -c)

  47(20 -c) = 40(15 +c) . . . . . . multiply by (20-c)(15+c)

  940 -600 = 40c +47c . . . . . add 47c-600

  340 = 87c . . . . . . . . . . . . . . . simplify; next divide by 87

  c = 340/87 ≈ 3.9080 . . . . mi/h

The speed of the current is about 3.9 mi/h.

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Find f(6) if f(x)=x^2 divided by 3x+x
Alinara [238K]
So, if I'm understanding you correctly, f(x)=x^2 divided by 3x+x, or
f(x) = (x^2)/(3x+x)
f(6) --> plug the 6 in to all values of x --> f(6) = (6^2)/(3×6 + 6) = 36/(18+6)
= 36/24 --> both are divisible by 12, so 36/12=3 and 24/12=2, now we have the reduced (simplified) answer:
f(6) = 3/2, or 1 1/2, or 1.5
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Find the slope of the line that passes through the points<br><br> A(0, 2) and B(4, –1).
kati45 [8]

Slope=M=y2-y1/X2-X1=

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3 years ago
Complete the square for the expression, then factor the trinomial.
Nuetrik [128]

Answer:

Completing the square we get: (x-2)^2-(2)^2

and factoring the term we get: x(x-4)

Step-by-step explanation:

We need to complete the square for the expression x^2-4x

For completing the square the expression would be of form a^2+2ab+b^2=(a+b)^2

For given expression we have to add (2)^2 and subtract to make it complete the square.

x^2-2(x)(2)+(2)^2-(2)^2\\(x-2)^2-(2)^2

Now, we have to factor the polynomial using formula (a)^2-(b)^2=(a-b)(a+b)

So, (x-2)^2-(2)^2\\=(x-2-2)(x-2+2)\\=(x-4)(x-0)\\=x(x-4)

Completing the square we get: (x-2)^2-(2)^2

and factoring the term we get: x(x-4)

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Both the work and explanation is in the picture.

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Use the Quotient Rule to find the UNSIMPLIFIED version of the derivative. R(w)=3w+w^4/ 2w^2+1.
PolarNik [594]

From your previous questions, you know

(3<em>w</em> + <em>w</em>⁴)' = 3 + 4<em>w</em>³

(2<em>w</em>² + 1)' = 4<em>w</em>

So by the quotient rule,

<em>R'(w)</em> = [ (2<em>w</em>² + 1)•(3<em>w</em> + <em>w</em>⁴)' - (3<em>w</em> + <em>w</em>⁴)•(2<em>w</em>² + 1)' ] / (2<em>w</em>² + 1)²

That is, the quotient rule gives

<em>R'(w)</em> = [ (denominator)•(derivative of numerator) - (numerator)•(derivative of denominator) ] / (denominator)²

I'm not entirely sure what is meant by "unsimplified". Technically, you could stop here. But since you already know the component derivatives, might as well put them to use:

<em>R'(w)</em> = [ (2<em>w</em>² + 1)•(3 + 4<em>w</em>³) - (3<em>w</em> + <em>w</em>⁴)•(4<em>w</em>) ] / (2<em>w</em>² + 1)²

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3 years ago
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