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Mathematics 18 Online
OpenStudy (anonymous):

Solve the following inequality. write the solution set using interval notation.

OpenStudy (anonymous):

OpenStudy (anonymous):

thats the question and how the answer must be.

jimthompson5910 (jim_thompson5910):

Multiply both sides by 40 to clear out the fractions \[\Large \frac{6x+2}{8}-\frac{2x-8}{5} \le -4\] \[\Large 40*\left(\frac{6x+2}{8}-\frac{2x-8}{5}\right) \le 40*(-4)\] \[\Large 40*\left(\frac{6x+2}{8}\right)+40*\left(-\frac{2x-8}{5}\right) \le 40*(-4)\] \[\Large 5*\left(6x+2\right)-8*\left(2x-8\right) \le -160\] Do you see how to finish up?

OpenStudy (anonymous):

why is it 40? and i would distribute the 5 out into the 6X+2 then the 8 into the 2x-8 and keep going until i can take the left side and either divide the right by it or the left by the right.

jimthompson5910 (jim_thompson5910):

because 8*5 = 40 is the LCD

jimthompson5910 (jim_thompson5910):

if you multiply both sides by the LCD, then you clear out the fractions

OpenStudy (anonymous):

ohhhhhhhhhhh ok. am i correct in the final steps?

jimthompson5910 (jim_thompson5910):

` i would distribute the 5 out into the 6X+2 then the 8 into the 2x-8` correct `keep going until i can take the left side and either divide the right by it or the left by the right` these steps seem a bit vague to me

OpenStudy (anonymous):

if the number on the left of the less than or equal to sign is less than 160 divide 160 by it. if it is more than 160 than divide that number by 160?

jimthompson5910 (jim_thompson5910):

when you distributed, what did you get?

OpenStudy (anonymous):

30x+10-16x-64≤-160

jimthompson5910 (jim_thompson5910):

the -64 should be +64

OpenStudy (anonymous):

14x-54≤-160

jimthompson5910 (jim_thompson5910):

since -8 times -8 = 64

OpenStudy (anonymous):

+54**

OpenStudy (anonymous):

didnt change the sign

jimthompson5910 (jim_thompson5910):

after distributing you should get `30x+10-16x+64≤-160` which simplifies to `14x+74≤-160` after you combine like terms

OpenStudy (anonymous):

14x≤-214

OpenStudy (anonymous):

oh i messed up somewhere

OpenStudy (anonymous):

had to do the +64

OpenStudy (anonymous):

14x≤234?

jimthompson5910 (jim_thompson5910):

close but no

jimthompson5910 (jim_thompson5910):

you lost a sign somewhere, it should be `14x≤-234`

OpenStudy (anonymous):

ah i put it in my calculator and forgot the negative!

OpenStudy (anonymous):

x=-16.4142857?

jimthompson5910 (jim_thompson5910):

leave it as a fraction and reduce as much as possible

OpenStudy (anonymous):

is it a fraction? i got a decimal when i divided

jimthompson5910 (jim_thompson5910):

234/14 can be reduced to ???

jimthompson5910 (jim_thompson5910):

hint: find the GCF of 234 and 14

OpenStudy (anonymous):

GCF=2?

jimthompson5910 (jim_thompson5910):

yes

OpenStudy (anonymous):

117/7

jimthompson5910 (jim_thompson5910):

divide each part of the fraction by 2 234/2 = 117 14/2 = 7 so 234/14 = 117/7

jimthompson5910 (jim_thompson5910):

good

OpenStudy (anonymous):

so what would the solution set be?

jimthompson5910 (jim_thompson5910):

so -234/14 = -117/7

jimthompson5910 (jim_thompson5910):

in the end, the solution would be \[\Large x \le -\frac{117}{7}\] what is this in interval notation?

OpenStudy (anonymous):

[-117,7]?

jimthompson5910 (jim_thompson5910):

draw a number line with -117/7 on it |dw:1443394703025:dw|

jimthompson5910 (jim_thompson5910):

the inequality \(\LARGE x \le -\frac{117}{7}\) means that we shade to the left of -117/7 on the number line |dw:1443394759997:dw|

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