20. - 23. are all correct.
24. A number raised to the zero power equals 1. 0 to the 0 power may be undefined according to some, but any number other than zero raised to the zero power is 1. We assume x is not equal to zero.
[tex] -2x^0 = -2 \times 1 = -2 [/tex]
25. To raise a product to a power, raise each factor to the power. Assume that none of the variables equal zero.
[tex] (11abx)^0 = 11^0 \times a^0b^0x^0 = 1 \times 1 \times 1 \times 1 = 1 [/tex]
26. Assume all variables are non-zero.
[tex] (xy)^0 - (pq)^0 = 1 - 1 = 0 [/tex]
