Solve for x: 7x + 21 > 0, x is a set of real numbers
a) x > -3
b) x < -3
c) x > 3
d) x < 3
2007-04-18 03:04:11 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
7x+21>0
7x>-21
X>-3
a
2007-04-18 03:11:51 · answer #1 · answered by A R 3 · 0⤊ 2⤋
The answer is a
x > -3
If x = -2
7(-2) + 21 > 0
-14 + 21 > 0
7 > 0 is correct
If x =-1
7(-1) + 21 > 0
-7 + 21 > 0
14 > 0 is correct
If x = 0
7(0) + 21 > 0
0 + 21 > 0
21 > 0 is correct
If x = 1
7(1) + 21 > 0
7 + 21 > 0
28 > 0 is correct
If you increase the value of x by 1, the inequality will hold true
2007-04-18 10:18:48 · answer #2 · answered by detektibgapo 5 · 0⤊ 0⤋
wow that is easy...
yet they all are getting it wrong (or I'm too damn tired to see that they wern't picking c...)
3*7 +21 = 42 which is much greater then 0 so c works, but the answer is actually a
.3*7 = -21 + 21 = 0
but since it is simply a greater than sign and not an equal to one x never will reach -3, just all numbers greater then that which will all be greater then 0 so your answer is a.
2007-04-18 10:13:42 · answer #3 · answered by l0uislegr0s 3 · 0⤊ 0⤋
7x + 21 = 0
7x + 21 - 21 = 0 - 21
7x = - 21
7x / 7 > - 21/7
x > - 21/7
x > - 3
The answer is a
- - - - - - -s-
2007-04-18 10:43:27 · answer #4 · answered by SAMUEL D 7 · 0⤊ 0⤋
The answer is a.
2007-04-18 10:09:23 · answer #5 · answered by Anonymous · 0⤊ 0⤋
a.
2007-04-18 10:08:06 · answer #6 · answered by lab_rat_4u 2 · 0⤊ 0⤋