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Mathematics 7 Online
OpenStudy (melissa_something):

Polynomial Inequality.. got stuck :/

OpenStudy (popitree):

question please

OpenStudy (melissa_something):

I got up to \[\frac{ x+4 }{ 2x-1} + \frac{ -3(2x-1) }{2x-1}=0\]

OpenStudy (melissa_something):

The original is x+4 / 2x-1 < 3

OpenStudy (popitree):

\[\frac{ x+4 }{ 2x-1 } < 3\]

OpenStudy (popitree):

x+4<6x-3

OpenStudy (popitree):

5x > 7 x > 7/5

OpenStudy (melissa_something):

7/5 is part of the answer, but I have no idea what u did lol

OpenStudy (jdoe0001):

one sec

OpenStudy (popitree):

to eliminate denominator, multiplied both side by (2x-1)

OpenStudy (jdoe0001):

\(\bf \cfrac{ x+4 }{ {\color{brown}{ 2x-1}} } < 3\impliedby cross-multiply \\ \quad \\ x+4<3\cdot {\color{brown}{ (2x-1)}}\implies x+4<6x-3 \\ \quad \\ 4+3<6x-x\implies 7<5x\implies \cfrac{7}{5}<x\)

OpenStudy (popitree):

And then just took x and constants in opposite sides of the inequality sign

OpenStudy (melissa_something):

Yeah I got that far, then got the first thing I put. I was gonna ask if I can cross the (2x-1) out

OpenStudy (melissa_something):

@jdoe0001 Oh okay! let me study this

OpenStudy (jdoe0001):

\(\bf \cfrac{ x+4 }{ {\color{brown}{ 2x-1}} } < 3\impliedby cross-multiply \\ \quad \\ x+4<3\cdot {\color{brown}{ (2x-1)}}\implies x+4<6x-3 \\ \quad \\ x+4+3<6x\cancel{-3+3}\implies x+7<6x\implies \cancel{x-x}+7<6x-x \\ \quad \\ 7<5x\implies \cfrac{7}{5}<x\) slower version notice, we "add" 3 and then "subtract" x

OpenStudy (melissa_something):

@jdoe0001 I dont get what you did in the 3rd line... is that where you added 3? From where and why?

OpenStudy (melissa_something):

I see where, but why? @jdoe0001

zepdrix (zepdrix):

You were ok up to this point?\[\large\rm x+4<6x-3\]

OpenStudy (melissa_something):

No I got up to x+7 < 6x then I didnt understand

OpenStudy (melissa_something):

:(

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