Which of the following is an irrational number: −1529, 0.343434..., 2√3, or 87.9821?
The irrational number among the given options is 2√3.
An irrational number is a number that cannot be expressed as a fraction (ratio) of integers and has an infinite number of non-repeating decimal places.
Out of the given options, 0.343434... is a repeating decimal, but it can be expressed as the fraction 343/999, so it is not an irrational number.
−1529 and 87.9821 are both rational numbers since they can be expressed as fractions.
Therefore, the number 2√3 is the only option that is an irrational number because it involves the square root of 3, which cannot be expressed as a fraction.