1) 12x -4 greater or equal than 7x+21

2) -1/3x - 7/9 greater or equal than 1/8 +3/7x

3) 3IxI - 5 = 10

1.)
12x - 4 >= 7x + 21
5x >= 25
x >= 5

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2.)
(-1/3)x - (7/9) >= (1/8) + (3/7)x
Multiply everything by 504
-168x - 392 >= 63 + 216x
-384x >= 455
x <= -455/394 or -1.1849

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3.)
3|x| - 5 = 10
3|x| = 15
|x| = 5
x = 5 or -5

www.quickmath.com can also help, however it doesn't show u the work, it only answers it for u.

this _>_ is my greater than or equal to sign k
1) 12x-4_>_7x+21
add 4 both sides
12x_>_7x+25
subtract 7x both sides
5x_>_25
divide by 5 both sides
x_>_5

2) -1/3x-7/9_>_1/8+3/7x
change to common denominator
-7/21x-56/72_>_9/72+9/21x
add 56/72 both sides
-7/21x_>_65/72+9/21x
subtract 9/21x both sides
-16/21x_>_65/72
divide both sides by -16/21

65. 21. 1365. 453. 151
72. 16. 1152. 384. 128
so x_>_151/128

3) 3|x|-5=10
add 5 both sides
3|x|=15
divide both sides by 3
|x|=5
simplify
x=5,-5

1) 12x - 4 >= 7x + 21

Add 4 to both sides:

12x >= 7x + 25

Subtract 7x from both sides:

5x >= 25

Divide both sides by 5:

x >= 5



2) Follow the same process. (Remember to flip the inequality sign if you multiply or divide both sides by a negative number.



3) 3IxI - 5 = 10

Add 5 to both sides:

3|x| = 15

Divide both sides by 3:

|x| = 5

which means that x = 5 or x = -5

1).
12x - 4 greater or equal than 7x + 21
12x - 4 ≥ 7x + 21
5x ≥ 25
x ≥ 5

2).
-1/3x - 7/9 greater or equal than 1/8 + 3/7x
-1/3x - 7/9 ≥ 1/8 + 3/7x
3/7x + 1/3x ≤ 7/9 + 1/8
16/21x ≤ 65/72
16/7x ≤ 65/24

3).
3IxI - 5 = 10
3IxI = 15
IxI = 5
x = -5, 5