1. I need help in solving the following compound inequality. I also need to write solution set in interval notation and graph. -1 < 3 - 2x < 11 The idea is to isolate x in the middle. Get rid of the 3 by adding -3 to all three sides: -1 < 3 - 2x < 11 -3 -3 -3 ------------------- -4 < -2x < 8 So we have -4 < -2x < 8 Now we divide all three siade by the coefficient of x, which is -2. But since we are dividing by a negative number that reverses the inequalities: -4 -2x 8 ———— > ————— > ———— -2 -2 -2 or 2 > x > -4 Which is the same as -4 < x < 2 On a number line this is graphed as --------o=================·------- -6 -5 -4 -3 -2 -1 0 1 2 3 4 It is an open circle at -4, because it is < and not <, and closed (dark circle) at 2, because it is < and not <. The interval notation is a shorthand for this graph: (-4, 2] The "(" on the left represents the open circle, the -4 is the left endpoint of the shaded part, the 2 is the right endpoint of the shaded part, and the "]" represents the closed circle. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 2. I need to graph the following absolute value inequality: |x+2y|(greater than or equal to) 6 First we draw the boundary graph, which is found by replacing the > sign by = |x + 2y| = 6 x + 2y = 6 or x + 2y = -6 So we graph both these lines, which are parallel:This gives us three regions, the region above the red line, the region between the two lines, and the region below the green line. We select an arbitrary test point in each of the three regions to see which we shade as the solution set, and which we don't. I arbitrarily select the point (0,5) as a test point for the region above the red line and substitute it into the original inequality: |x + 2y| > 6 |0 + 2(5)| > 6 10 > 6 This is true so we shade the part above the red line. I arbitrarily select the point (0,0) as a test point for the region between the two lines and substitute it into the original inequality: |x + 2y| > 6 |0 + 2(0)| > 6 0 > 6 This is false so we do not shade the region between the lines: I arbitrarily select the point (0,-5) as a test point for the region below the green line and substitute it into the original inequality: |x + 2y| > 6 |0 + 2(-5)| > 6 10 > 6 This is true so we shade the part below the green line. Now I can't shade on here but you can on your paper. Shade the big area above the red line, and the big area below the green line. But do not shade the region between the two lines. Also draw both lines solid because the inequality symbol is > and not >. If it had been > instead you would draw the line dotted. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3. I need to graph the following compound inequality: 3-xy+5 Sorry, you mistyped that. There's no >, <, > or < @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 4. I need to determine whether -4 satisfies the following compound equality: -3x > 0 AND 3x - 4 < 11 Plug it in and see if it's true or false: -3x > 0 AND 3x - 4 < 11 -3(-4) > 0 AND 3(-4) - 4 < 11 4 > 0 AND -12 - 4 < 11 4 > 0 AND -16 < 11 They are BOTH true so yes, it satisfies the compound inequality. If either had been false then it would not have satisfied it. If it had been OR instead of AND only one side would have needed to be true for it to have been a solution. Edwin