To get the prime factorization of a number, apply divisibility rules.
(a) 18
Since 18 is an even number, it is divisible by the smallest even number which is 2 (`18-:2=6` ). So,
`18 = 2 xx 9`
Then, factor 9 further. Since 9 is an odd number and a...
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To get the prime factorization of a number, apply divisibility rules.
(a) 18
Since 18 is an even number, it is divisible by the smallest even number which is 2 (`18-:2=6` ). So,
`18 = 2 xx 9`
Then, factor 9 further. Since 9 is an odd number and a multiple of 3, then it is divisible by 3 (`9-:3=3` ).
`18 =2xx3xx3`
Now that factors are all prime numbers, express the repeated factors in exponent form.
Therefore, `18=2xx3^2` .
(b) 20
20 is an even number. So,applying the divisibility rule for even numbers, its factor will be:
`20=2xx10`
10 is an even number too. So it can be factor further by applying the same rule.
`20=2xx2xx5`
Now that the factors are all prime numbers, express the repeated factors in exponent form.
Thus, `20=2^2xx5` .