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I would like some help please. Thanks! Question: Find three consecutive odd integers such that four times the sum of the first and third integer is five more than the product of three and the second number.

 Oct 11, 2014

Best Answer 

 #3
avatar+130081 
+5

Geno's answer is good....let me see if I can break it down more for you....

Let the first integer = x

Then, the next odd integer is just two more = x + 2

And the 3rd odd integer is just two more than the second = (x + 2) + 2 = x + 4

Now...let's look at what's said (in pieces)

"The sum of the first and the third" is just x  + (x + 4)   = 2x + 4

So....."Four times the sum of the first and the third" is just  4(2x + 4)     =  (A)

And "The product of 3 and the second number means to multiply the second number by 3 =  3(x + 2)  = (B)

Now....here's the tricky part.....

We're told that (A) is 5 more than (B)...this must mean that, if I subtracted 5 from (A), I'd end up with (B) !!

Therefore......(A) - 5 = (B)

And, substituting in for (A) and (B),we have

4(2x + 4) - 5 = 3(x + 2)

Simplify both sides

8x + 16 - 5 = 3x + 6

8x + 11 = 3x + 6

Subtract 6 and 8x from both sides

5 = -5x

Divide both sides by -5

-1 = x

That's the first integer

And the second is just  x + 2 = -1 + 2 = 1

And the third is just x + 4 = -1 + 4 = 3

And that's it !!!

 

 Oct 11, 2014
 #1
avatar+23253 
+5

If  x  is the smallest odd integer, then  x + 2  will be the next larger odd integer, and  x + 4  will be the largest of the three odd integers.

4[ (x) + (x + 4) ] = 5 + 3(x + 2)

4( 2x + 4 )  =  5 + 3x + 6

8x + 16  =  3x + 11

5x  =  -5

So the smallest integer is  -1.

Use this to find the other two.

 Oct 11, 2014
 #2
avatar
0

Thanks for your help but I am still totally lost on this one.

 Oct 11, 2014
 #3
avatar+130081 
+5
Best Answer

Geno's answer is good....let me see if I can break it down more for you....

Let the first integer = x

Then, the next odd integer is just two more = x + 2

And the 3rd odd integer is just two more than the second = (x + 2) + 2 = x + 4

Now...let's look at what's said (in pieces)

"The sum of the first and the third" is just x  + (x + 4)   = 2x + 4

So....."Four times the sum of the first and the third" is just  4(2x + 4)     =  (A)

And "The product of 3 and the second number means to multiply the second number by 3 =  3(x + 2)  = (B)

Now....here's the tricky part.....

We're told that (A) is 5 more than (B)...this must mean that, if I subtracted 5 from (A), I'd end up with (B) !!

Therefore......(A) - 5 = (B)

And, substituting in for (A) and (B),we have

4(2x + 4) - 5 = 3(x + 2)

Simplify both sides

8x + 16 - 5 = 3x + 6

8x + 11 = 3x + 6

Subtract 6 and 8x from both sides

5 = -5x

Divide both sides by -5

-1 = x

That's the first integer

And the second is just  x + 2 = -1 + 2 = 1

And the third is just x + 4 = -1 + 4 = 3

And that's it !!!

 

CPhill Oct 11, 2014
 #4
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0

Thank you CPhill! I think I understand now.

 Oct 11, 2014

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