Tuesday

July 22, 2014

July 22, 2014

Posted by **rob** on Friday, March 23, 2007 at 10:05pm.

What equation would I use to solve this problem i have no idea

Let V be her speed going out, so V+5 will be her speed coming back. Let the distance each way be D.

L/V = 5 hours

L/(V+5) = 4 hours

Two equations, two unknowns. Solve for V

L= 5 V

L = 4V + 20

Subtract the second equation from the first, and rearrange.

V = 20 mi/h

I saw another tutor work a similar problem this way with a table and I thought it made the problem simper to see how to solve it.

..........rate....time......d=r*t

going......r.......5 hrs....d=r*5

return.....r+5.....4 hrs....d=(r+5)*4

The distance is the same; therefore,

d=d

r*5=(r+5)*4

solve for r.

the d=r*t = 5r.

Post your work if you get stuck.

Geometry.the volume of the boxis represented by (x^2+5x+6)(x+5). find the polynomial that represent the area of the bottom of the box.

Ok Igot this much not sure where to go after this

r*5=(r+5)*4

5r=(r+5)*4

5r=4(r+5)

5r=(4*r)+(4*5)

5r=4r+20

5r-4r=20

r=20

If i am right the the distance is 100 miles

where do I go from here to find the speed each way ?

Read my first answer again. It tells you how to get the speeds. Knowing the distance and the time also lets you computer either speed

DrBob, that was me

I have taught dist-rate-time problems using the chart for over 35 years, there is no better way.

It makes it so easy to see.

The trinomial factors easily into (x+2)(x+3).

So your 3 dimensions of the box obviously are x+2,x+3, and x+5

From the question we cannot tell which are the length width or height.

So the expansion of any two of them could give you the area of the bottom.

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