How many even natural-number factors does n = (2^2)(3^1)(7^2) have?
ok so i think that all the odd factors are 3, 21, 150, 49, but i'm not sure about the rest :(
4 x 3 x 49 = 588
Factors (from a website):
1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 49, 84, 98, 147, 196, 294, 588,
-1, -2, -3, -4, -6, -7, -12, -14, -21, -28, -42, -49, -84, -98, -147, -196, -294, -588 Pick the ones you like and count them up !
Here's a way to figure this
2^1 = 2
2^2 = 4
2 * 3 = 6
2^2 * 3 = 12
2* 7 = 14
2^2 * 7 = 28
2 * 3 * 7 = 42
2^2 *3 * 7 = 84
2*7^2 = 98
2^2 * 7^2 = 196
2 *3 * 7^2 = 294
2^2 * 3 * 7^2 = 588
[ Note....negative factors are not "natural" numbers ]
How many even natural-number factors does \(n = (2^2)(3^1)(7^2)\) have?
\(\begin{array}{|llcll|} \hline 2^{\color{red}2} * & 3^{\color{blue}1} * 7^{\color{green}2} \\\\ ({\color{red}2}+1 ) *& ({\color{blue}1}+1) * ({\color{green}2}+1) = 3*2*3 &=& 18~ \text{divider} \\ & ({\color{blue}1}+1) * ({\color{green}2}+1) = 2*3 &=& 6~ \text{odd divider} \qquad (\text{odd*odd=odd})\\ \hline &&& 18-6 = \mathbf{12}~ \text{even divider} \\ \hline \end{array} \)