Which of the following is an irrational number: −1529 , 0.343434..., 2√3 , or 87.9821?
An irrational number is a number that cannot be expressed as a fraction (or ratio) of two integers.
Out of the options, 0.343434... can be expressed as the fraction 34/99, so it is not irrational.
−1529 and 87.9821 can be expressed as integers, so they are not irrational.
2√3 cannot be expressed as a fraction of two integers, so it is irrational.
Therefore, 2√3 is the irrational number among the options provided.