Thread: absolute value..2 different answer

absolute value

I getting a different answer...don't know why

|3-4x|≥2

what i did was=====> i made it in to 2 parts ===>3 - 4x ≥ 2 and 3 - 4x ≥-2

my final answer that i got is
1/4≥x (first part) and (second part) 5/4 ≥ x

but the teacher got
1/4≥x and 5/4 ≤ x
why did the sign change for the last one? i dont get it

Originally Posted by Candy101

absolute value

I getting a different answer...don't know why

|3-4x|≥2

what i did was=====> i made it in to 2 parts ===>3 - 4x ≥ 2 and 3 - 4x ≥-2

my final answer that i got is
1/4≥x (first part) and (second part) 5/4 ≥ x

but the teacher got
1/4≥x and 5/4 ≤ x
why did the sign change for the last one? i dont get it

Redo the second problem: 3-4x≥-2, first subtract 3: 3-3-4x≥-5 = -4x≥-5
then, divide by NEGATIVE 4 = 5/4≤ x (or you could say x≥5/4). The reason the sign changed is because you divided by a NEGATIVE number. Any time you divide by a negative number, the direction of the sign changes.

assuming you get that:


and

Using the second inequality and multiplying both sides by -1



Note: When you multiply both sides of an inequality by -1, you have to flip the direction of inequality

For example:

So

Originally Posted by Candy101

absolute value

I getting a different answer...don't know why

|3-4x|≥2

what i did was=====> i made it in to 2 parts ===>3 - 4x ≥ 2 and 3 - 4x ≥-2

my final answer that i got is
1/4≥x (first part) and (second part) 5/4 ≥ x

but the teacher got
1/4≥x and 5/4 ≤ x
why did the sign change for the last one? i dont get it

Hi Candy101,



Understand this basic principal:

If |a| > b, then a > b or a < -b

Therefore,

how to graph this

y=3|x+2|-9

it says graph: vertex and intercepts

by the way how do u find the vertex of any problem?

thanks

Originally Posted by Candy101

how to graph this

y=3|x+2|-9

it says graph: vertex and intercepts

by the way how do u find the vertex of any problem?

thanks

HI

you can start by sketching y=3|x+2| first . Find its intercepts

when x=0 , y=6

when y=0 , x=-2

so there will be a line passing through 6 to -2 , then the line is reflected since there is a modulus , it cant take negative values of y .

After this , shift the graph down for 9 units .

Originally Posted by mathaddict

HI

you can start by sketching y=3|x+2| first . Find its intercepts

when x=0 , y=6

when y=0 , x=-2

so there will be a line passing through 6 to -2 , then the line is reflected since there is a modulus , it cant take negative values of y .

After this , shift the graph down for 9 units .

how did you get 6 and -2?
can u please show or explain ur steps?
thanks,

Originally Posted by Candy101

how did you get 6 and -2?
can u please show or explain ur steps?
thanks,

Put x and y =0 respectively to get the intercepts (points where the line cuts the x and y axis )