Linear Inequalities Flashcards
What do you do when you multiply or divide by a negative in a linear inequality?
FLIP the inequality
10 < 2x + 4 < 24 ?
when you done thing to anyone of these parts you have to do it to each of them so -4
6 < 2x < 20
then /2
= 3 < x < 10
** if this were negative you would flip ALL of the inequalities
what does “at least” mean ?
> or equal to
when you see 0 < x^2 < 1 what do you know about x?
you know that x can be a positive or negative because the x^2 will get rid of the negative sign
if ab > 0 and a < 0 which of the following is greater than b?
- -0.5
- 0
- .5
by looking at a <0 you know a is a negative so you can solve ab > 0 by dividing by a BUT you know a is a negative and when you divide by a negative you have to FLIP the sign so you get b < 0
SO anything greater than b would be 0 and .5
If 7(x + 1) = 8(y - 1) and y and x are both positive integers, what is the least possible value of x + y?
A. 1 B. 2 C. 7 D. 9 E. 15
Where should you start with solving this in terms of PITA?
start with C and do x + y = 7 and then solve for x so x = 7 - y and then plug in that value for x and see if the equations are equal. Keep going until you find the correct answer.
0 <= |x|/2 <= 8
QA: The absolute value of the least possible value of x
QB: The absolute value of the greatest possible value of x
A B C D
they are the same, C! x = -16 or 16 since they have the absolute value, the values are the same