Ok i need to know how to check my answer for this problem -2x + 4 > 12?

Choose a number which is less than -4 and put it into -2x + 4. The answer you get should be more than 12 if you're right.

Example: let x = -10 so -2x + 4 = 20 + 4 = 24 which is bigger than 12.

HOWEVER - this only verifies it in certin cases, but doesn't actually prove it's correct. If it's wrong, then you know you've a problem.

The 6 works. The left hand side is log(64) The right side is 2 log(8) But the law of logarithms states that 2log(8) = log(64) (remember log(a^b)=b*log(a), with a=8 and b=2) It is the -2 that does not work. Log(0) is UNDEFINED. log(x) is only defined for positive x. Substituting x=-2 does not yield a true equation, so x=-2 is not a solution.

sub in a number as x and if it is correct your value will be greater than 12, eg. (-7)

-2(-7) + 4 > 12
14 + 4>12
18>12

but just have a bit more confidence in yourself and you won't need to check it.

Hope that helps!

:D

once you find "x" simply plug it in. if it ends up being true (>12, >8, etc) then your solution is correct. if it's incorrect, it's time to check it once more, and then start over again.

-2x + 4 > 12
-2x > 12 - 4
-2x > 8
x < 8/(-2)
x < -4

- 8 > 2x
x < - 4

Which agrees with your solution.

do several checks with numbers less than -4 (-5, -6, -7, etc)
-2(-5) + 4 > 12 => 10 + 4 > 12 => 14 > 12 :)
-2(-10) + 4 > 12 => 20 + 4 > 12 => 24 > 12 :)
-2(-20) + 4 > 12 => 40 + 4 > 12 => 44 > 12 :)

All you have to do is take any number less than -4 and substitute it for x.

For example:
-2 (-5) + 4 > 12
10 + 4 > 12
14 > 12

your answer is absolutely right. to check it substitute -4 (your answer) for x in the original problem. substitute the equal sign for >.

-2*-4 +4 = 12
8+4 = 12
12=12

try sub x = -5
10 + 4 > 12 checked