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OpenStudy (pixiedust1):

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jimthompson5910 (jim_thompson5910):

`The length of a rectangle is 2 ft more than four times the width` means L = 4W+2 `perimeter is less than 34 ft ` means P < 34 P < 34 2L+2W < 34 2(4W+2)+2W < 34 8W+4+2W < 34 10W+4 < 34 10W+4-4 < 34-4 10W < 30 10W/10 < 30/10 W < 3 If W is an integer, then the highest W can be is 2. The value of W cannot be 3 since W < 3 So you have the correct answer. Nice job

jimthompson5910 (jim_thompson5910):

`do you know much about set builder notation?` yes I do

jimthompson5910 (jim_thompson5910):

`Solve and write the solution in set-builder notation. 3x-1>2x+2` `And I said that x>3 and {x|x>3}` {x|x>3} is the correct way to write x > 3 in set builder notation

jimthompson5910 (jim_thompson5910):

`Solve and write the solution in set-builder notation 3x+1<=7x-15` `x>=4` `{x|x>=4}` also correct

jimthompson5910 (jim_thompson5910):

`And the final one, -5<3x+4<16` `And my answer was -3<x<4` `{x|-3<x<4}` also correct

jimthompson5910 (jim_thompson5910):

yes. You did great

jimthompson5910 (jim_thompson5910):

interval notation and set builder notation are slightly different. They represent the same idea though

jimthompson5910 (jim_thompson5910):

for example, we can say 3 < x < 10 or we can write (3,10) the `(3,10)` in interval notation means start at 3 and end at 10. Exclude 3 from the interval. Exclude 10 from the interval

jimthompson5910 (jim_thompson5910):

another example 2 < x <= 7 is written as (2,7] notice the use of a square bracket the `(2,7]` in interval notation means start at 2 and end at 7. Exclude 2 from the interval. Include 7 in the interval

jimthompson5910 (jim_thompson5910):

] means include the endpoint ) means exclude the endpoint

jimthompson5910 (jim_thompson5910):

if you want to write something like x > 5, then you'd write (5, infinity) if you want to write something like x >= 5, then you'd write [5, infinity) if you want to write something like x < 5, then you'd write (-infinity, 5) if you want to write something like x <= 5, then you'd write (-infinity, 5] never use square brackets for infinity. You never can include infinity since it goes on forever

jimthompson5910 (jim_thompson5910):

when you wrote `3/5x-2<3/10-x` did you mean to write \[\Large \frac{3}{5}x-2 < \frac{3}{10}-x\] or no?

jimthompson5910 (jim_thompson5910):

`x<23/16` `(-infinity, 23/16)` are both correct

jimthompson5910 (jim_thompson5910):

I'm glad it makes more sense now

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