Verify the: `18xx[7+(-3)]=[18xx7]+[18xx(-3)]`

Verify the following. 18 xx [7 + (-3)] = [18 xx 7] + [18 xx (-3)]

Verify: 18times[7+(-3)=[18times7]+[18times(-3)]

Verify the following: (3xx7)xx5=3xx(7xx5)

18/11 xx (-33)/45

Verify [(-5) xx 2)] xx 3 = (-5) xx [(2 xx 3)]

Find the value of (-2) xx (-3) xx (4) xx (-7).

Find 1.7 xx 3

(-105)/72 xx 18/15

Find the each of the product: (-18)xx(-5)xx(-4)=

The dissociation coustant of H_(2)O, H _(2)Se and H_(2) Te are 1.8 xx 10 ^(-16) , 1.4 xx 10 ^(-7) , 1.3 xx 10 ^(-4)and 2.2 xx 10 ^(-3), respectively. What do these values denote ?