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Mathematics 7 Online
OpenStudy (anonymous):

Need help with domain and range!!

OpenStudy (anonymous):

Find the domain and range of the function \[y=2\sqrt{3x+4-5}\]

OpenStudy (anonymous):

Will fan!!

OpenStudy (jango_in_dtown):

3x+4-5? is it correct?

OpenStudy (jango_in_dtown):

@Harley-Quinn

OpenStudy (anonymous):

that is under a Square root https://www.connexus.com/content/media/459431-3172011-84450-AM-1622409520.png

OpenStudy (jango_in_dtown):

ok so 3x+4-5 >=0 implies 3x>=1 implies x>=1/3 so the domain is [1/3,infinity) and range is the set of all positive real numbers

OpenStudy (anonymous):

Would that be \[x \ge-\frac{ 4 }{ 3 } ;y \ge-5\] \[x \ge \frac{ 4 }{ 3 };y \ge -5\] \[x \le-\frac{ 4 }{ 3 };y \le-5\] or \[x \ge-\frac{ 4 }{ 3 };y \ge5\]

OpenStudy (anonymous):

@jango_IN_DTOWN

OpenStudy (jango_in_dtown):

the term inside the square root is not correct..... you post the question properly..

OpenStudy (anonymous):

\[y=2\sqrt{3x+4-5}\]

OpenStudy (campbell_st):

looking at the solutions I think the problem is \[y = 2\sqrt{3x + 4} - 5\]

OpenStudy (anonymous):

yes

OpenStudy (jango_in_dtown):

uhhhh I kept on telling you look at the questoin

OpenStudy (jango_in_dtown):

its ok @campbell_st will help you,:)

OpenStudy (campbell_st):

ok... so the domain: you can't that the square root of a negative number.... in terms or real numbers so then the part inside the square your has to be greater than or equal to zero so you need to solve \[3x + 4 \ge 0\] this will be the domain. Now for the range if the square root value is zero... what is the value of y...?

OpenStudy (campbell_st):

the range will basically be all values going up from the y- intercept... hope that helps

OpenStudy (anonymous):

i am not good with this at all sorry...

OpenStudy (campbell_st):

so you can't solve \[3x + 4 \ge 0\] could you solve 3x + 4 = 0.....?

OpenStudy (anonymous):

i am not sure if it is just me but the bottom one makes more sense some how... you would subtract 4 from both sides??

OpenStudy (campbell_st):

well the same steps will apply to the inequality subtracting 4 is a good start \[3x \ge -4 \] now get a single x.... the answer will give the domain...

OpenStudy (anonymous):

you would divide 3 so \[-\frac{ 4 }{ 3 }\]

OpenStudy (campbell_st):

great so you have the domain \[x \ge -\frac{4}{3}\] now the range, find the y- intercept... let \[\sqrt{x3x + 4} = 0\] so the equation becomes \[y = 0 - 5\] where does the curve cut the y-axis..?

OpenStudy (anonymous):

at -5??

OpenStudy (campbell_st):

great so that is the lowest part of the range... and then the values of y just keep increasing. \[increasing~~~ \ge\] so what answer do you think matches the domain and range..?

OpenStudy (anonymous):

\[y \ge-5\] for range and \[x \ge-\frac{ 4 }{ 3 }\] for domain

OpenStudy (campbell_st):

great... so now you have the answer

OpenStudy (anonymous):

Thank you <3

OpenStudy (anonymous):

can you help me with one more?

OpenStudy (anonymous):

@campbell_st

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