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3 years ago

6

a 15-ft ladder is leaning against one wall of an alley 9 ft wide. the ladder slips, its top sliding down the wall, its foot slid

ing across the alley and striking the opposite wall at a speed of 4 ft/sec. How fast is the top of the ladder falling at that instance?

1 answer:

blagie [28]3 years ago

5 0

2x dx/dt +2y dy/dt = 0
<span>x dx/dt + y dy/dt = 0 </span>
<span>9*4 + 12 dy/dt = 0 </span>
<span>dy/dt = - 3 ft/sec </span>

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Answer:

1) m=15 and r =5

2) 4 and 2 ml

3) x= 0.5 and y = -1

Step-by-step explanation:

given that m multiple choice questions and r extended response questions.

Also given that a) m+r = total no of questions =20 ... i and

2m+6r = total time taken = 60 ... ii

b) Divide second equation by 2, m+3r = 30 ... iii

m+r = 20 ... i

Subtract to get 2r =10 or r =5

m = 20-5 = 15

Verify: m+r = 15+5 =20

and 2m+6r = 30+30 = 60 minutes.

Hence verified

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2) Let a litres of 20% solution and b litres of 50% solution be mixed

a) Then total volume = 6 ml = a+b ... i

Resulting solution = 30% of 6 ml = 1.8 = 0.2a+0.5b ... ii

b) Solve i and ii

b = 6-a: substitute in ii.

0.2a + 3-0.5a = 1.8

Or a = 4 ml and b = 2ml

Verify: Total volume = a+b =6ml and

concentration = 0.2(4)+0.5(2) = 1.8 = 30% of 6 ml.

Thus verified

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3) 2x-3y=4 ...i

2x-5y =6... ii

Because x term has the same coefficient in both the equations, elimination is easier.

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So answer is x = 0.5 and y =1

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Answer:

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Step-by-step explanation:

<u>Step 1: Determine the area of the left rectangle</u>

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