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Mathematics 7 Online
OpenStudy (anonymous):

Hey I need help on ONE question it is very short and I'm assuming it is very simple but I forgot how to do it. Help appreciated rewarding medals :D

OpenStudy (anonymous):

\[|2x+3| \le 15\]

OpenStudy (anonymous):

Solve for x.

OpenStudy (solomonzelman):

\(\Large\color{blue}{ │2x+3│≤ 15 }\) gives \(\Large\color{blue}{ -15≤2x+3≤ 15 }\)

OpenStudy (solomonzelman):

subtract 3 from each part, \(\Large\color{blue}{ -15\color{red}{ -3 }≤2x+3\color{red}{ -3 }≤ 15\color{red}{ -3 } }\)

OpenStudy (anonymous):

Any specific reason why the signs change direction in your first step?

OpenStudy (solomonzelman):

Puerto Rico scored against greece just now

OpenStudy (anonymous):

Lol is that good or bad? Who are you going for?

OpenStudy (solomonzelman):

I am not going for those teams. I am a fan of Christiano Ronaldo, he is the best dribbler, but now I am going for Brazil.

OpenStudy (anonymous):

Ah okay :D

OpenStudy (anonymous):

I don't know much about soccer x_x

OpenStudy (solomonzelman):

It's okay :) ..... remember this formula, \(\Large\color{blue}{ │ ax+b│≥c ~~~~~~~~gives, }\) \(\Large\color{blue}{ -c ≥ ax+b≥c }\)

OpenStudy (anonymous):

Writing it down.

OpenStudy (solomonzelman):

seriously, or is that a joke ;) (?)

OpenStudy (solomonzelman):

in that formula a,b and c are numbers (meaning constants)

OpenStudy (anonymous):

Lol seriously I wrote it down on my worksheet :P But wait... in my original problem it is a LESS THAN OR EQUAL TO sign, in your formula it is GreaterThanOrEqualTo Does it make a difference or does the formula remain the same?

OpenStudy (anonymous):

Oh wait you just change the signs according to the problem you're working with?

OpenStudy (anonymous):

I'm assuming

OpenStudy (phi):

by definition if x is positive, then |x| = x if x is negative, then |x| = -x (the -x will be positive) if you have a relation |x| < A then you have two possibilities. x is positive, and you have the relation x < A or x is negative, and you have the relation -x < A in the latter instance, we can re-write by add +x to both sides to get 0 < A+x and then add -A to both sides to get -A < x or x > -A you have two possible relations you must simplify x> -A and x < A sometimes people write it as -A < x < A

OpenStudy (solomonzelman):

\(\Large\color{blue}{ │\color{red}{a}x+\color{red}{b} │ ≥ \color{red}{c} }\) \(\Large\color{blue}{ \color{red}{-c}≥\color{red}{a}x+\color{red}{b} ≥ \color{red}{c} }\) OR \(\Large\color{blue}{ │\color{red}{a}x+\color{red}{b} │ ≤ \color{red}{c} }\) \(\Large\color{blue}{ \color{red}{-c}≤\color{red}{a}x+\color{red}{b} ≤ \color{red}{c} }\)

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