Question 84440
Ok.
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1º Question your answer is right.
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2º and 3º questions  {{{abs(3x) > -9}}} and {{{abs(6x - 15)> -15}}}
-What you need to know is: {{{abs(Number)>0}}} (is always positive). --In this case for any real number x; {{{abs(3x)}}} {{{will}}} {{{be > -9}}}, the same for  {{{abs(6x - 15)> -15}}}. Example: {{{abs(-4)>-7}}} -->{{{4>-7}}}.
The answer is the all real number.
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<p></p>3º Question, your answer is right:
<p></p>{{{abs(2x - 5) - 8<=3}}}
<p></p>{{{2x-5}}} if {{{x>=5/2}}}
{{{-2x+5}}} if {{{x<5/2}}}
<p></p>{{{(2x-5)-8<=3}}}-->{{{x<=8}}}
{{{(-2x+5)-8<=3}}}-->{{{x>=-3}}}
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---------------{{{5/2}}}----------{{{8}}}---->
{{{-3}}}---------{{{5/2}}}------------------>
<p></p>{{{-3}}}-----------------------{{{8}}}----->
<p></p>Answer: {{{-3<=x<=8}}}