600+105x ≤ 750+80x, what is x?

Hi, I have another question

y=600+105x ≤ 750+80x

what is x?

the answer key says it x≤ 6; however, they didn’t change the sign when dividing both sides.

the answer I got was x≥6

(I also wanted to mention that I asked two questions and they are both from the deleted practice test 4. Do you know why practice tests 2 and 4 are deleted? Would it be because there are mistakes?)

What is the solution set of the equation above?

Hello; I have a question.

sqrt(x-2)=x-4

what is the solution set of the equation above?

a){3,6} b) {2} c) {3} d) {6}

the answer I got was a) but the answer key said it’s incorrect because 3 is an extraneous solution; however, I don’t understand why it’s an extraneous solution. I plugged in 3 and 6 back into the equation and both worked out.

for plugging in 3:
sqrt(3-2)=3-4 –> sqrt(1)=-1 –> -/+1=-1 does the square root of 1 not include -1?