mpls配置实例:初二数学 不等式

原式=4x+a>3
4x>3-a
x>(3-a)/4
原式=2x+1>0
x>-1/2

因为关于x的不等式(4x+a)/3 >1的解都是不等式
-(2x+1)/3 <0的解
所以(3-a)/4>=-1/2
所以a<=5

原式=4x+a>3
4x>3-a
x>(3-a)/4
原式=2x+1>0
x>-1/2

因为关于x的不等式(4x+a)/3 >1的解都是不等式
-(2x+1)/3 <0的解
且x>-1/2
所以(3-a)/4=-1/2
a=5

原式=4x+a>3
4x>3-a
x>(3-a)/4
原式=2x+1>0
x>-1/2

因为关于x的不等式(4x+a)/3 >1的解都是不等式
-(2x+1)/3 <0的解
所以(3-a)/4>=-1/2
所以a<=5

SweetHarmony你是中国人?你好像不能打中国字呀

Let's see if this makes sense:

-(2x+1)/3 < 0
(2x+1)/3 > 0 If the negative of the left side is negative (<0), then the negative of that must be positive (>0)

(2x+1) > 0 If a third (1/3) of something is positive (>0), then itself must be positive

2x > -1 Subtrate 1 from both sides

x > -(1/2) Divide both sides by 2

4x > -2 Multiply both sides by 4

~~~~
(4x+a)/3 > 1
(4x+a) > 3 Multiply both sides by 3
4x > 3-a Subtract a from both sides
and
4x > -2 from before

so...

3-a must be equal or less than -2
3-a <= -2
-a <= -5 subtract 3 from both sides
a >= 5 divide both sides by -1, flip sign when you do that.

3-a must be equal or less than -2 because both are less than 4x. For that to happen for sure, 3-a must be equal or smaller than -2.

Therefore, as long as a>=5, the two systems can hold the same solution set.

Edit:

Yes, I am Chinese. I was born and raised in BeiJing. However, I am currently attending college in New York City. I don't have Chinese input installed on the computer I'm using so I can't type in Chinese. If I use PinYin it will be even more confusing to understand. Ni shuo shi bu shi?