Final answer:
The addition of -2/3 and -3/10 results in -29/30, and 1.414213562 is an example of an irrational number. The number equivalent to 0.45 in fractional form is 9/20.
Step-by-step explanation:
The questions cover different areas of mathematics, including the addition of fractions and the identification of irrational numbers. To add fractions like -2/3 and -3/10, you would need a common denominator, which in this case is 30. The addition would then be -20/30 + -9/30 = -29/30. An irrational number is one that cannot be expressed as a simple fraction; it has an infinite number of non-repeating decimals. Therefore, out of the given examples, 1.414213562 (which looks like an approximation of the square root of 2) is an irrational number as it cannot be written as a fraction with integers in the numerator and denominator. Lastly, 0.45 can be expressed as the fraction 9/20, which is its equivalent in fractional form.