Can b always be greater than 0?

  • Thread starter Alpharup
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    Inequality
Thanks for pointing it out! In summary, your proof is incomplete as it does not consider the case where b is between 0 and -a. A complete proof would also need to consider this case in order to prove that b>0 always.
  • #1
Alpharup
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Let a>0. It is also true that a+b>0. Can we prove that b>0 always?
My attempt
b>-a... but 0>-a.

therefore min (b,0)>-a
case 1: b <0.
If, b <-a, then a <-b
so a+b <b-b
so, a+b <0.
Contradiction
Hence b>0.
Is my proof right?
 
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  • #2
Alpharup said:
Let a>0. It is also true that a+b>0. Can we prove that b>0 always?
My attempt
b>-a... but 0>-a.

therefore min (b,0)>-a
case 1: b <0.
If, b <-a, then a <-b
so a+b <b-b
so, a+b <0.
Contradiction
Hence b>0.
Is my proof right?
No.

a=20, b=-5
a>0
a+b=15>0

But b<0.

So where is the mistake in your proof?
 
  • #3
Alpharup said:
Let a>0. It is also true that a+b>0. Can we prove that b>0 always?
No.
 
  • #4
Yeah...I get it. b>-a...and b. an be between 0 and -a
 
  • #5
Yup, I did not consider between 0 and -a
 

Related to Can b always be greater than 0?

1. What is inequality?

Inequality refers to the unequal distribution of resources, opportunities, and rewards among individuals or groups in a society. It can manifest in various forms, such as income inequality, education inequality, and social inequality.

2. How is inequality measured?

Inequality can be measured using various indicators, such as the Gini coefficient, which measures income distribution; the Human Development Index, which measures overall well-being; and the Gender Inequality Index, which measures gender-based disparities.

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4. What factors contribute to inequality?

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5. How can we address inequality?

There are various approaches to addressing inequality, including implementing policies that promote equal access to education, healthcare, and job opportunities. Other solutions include redistributive policies, such as progressive taxation and social welfare programs, and addressing systemic issues, such as discrimination and unequal power dynamics.

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