Loading [MathJax]/jax/output/SVG/jax.js
 
+0  
 
+1
767
4
avatar

When all of the factors of 90 are multiplied together, the product can be expressed as 90^k. What is the value of k? 

 Mar 23, 2019
 #1
avatar+6251 
+1

listing the divisors of 901,2,3,5,6,9,10,15,18,30,45,90We can collect pairs of divisors that multiply to 90(1,90),(2,45),(3,30),(5,18),(6,15),(9,10)We see then that the product is 906

 

In general the product of the factors of n will be n12# of factors of nYou can determine the # of factors of n by taking the product of each of theexponents of the prime factors plus 1. For example 90=213251It has (1+1)(2+1)(1+1)=12 factors which multiply to 9012/2=906

.
 Mar 23, 2019
edited by Rom  Mar 23, 2019
edited by Rom  Mar 23, 2019
 #2
avatar+130466 
0

Factors of 90 =

 

 1 2 3 5  6 9 10 15 18 30  45  90

 

We  can write

 

(1 * 90) * (2* 45 )  *  (3 * 30)  * (5 * 18)   * (6 * 15 )  * ( 9 *10)  =

 

   90    *     90        *      90      *     90      *     90        *   90     =

 

90^6

 

k  =  6

 

cool cool cool

 Mar 23, 2019
 #4
avatar+532 
0

We know that if x is a factor of n, then nx is also a factor of n. Because 90 is not a perfect square, we can pair up the x's and the nx's and multiply them to get n. Because this is true for every number, we can count the number of factors of 90=2325. We can choose 2 ways for the exponent of 2, 3 for the exponent of 3, and 2 for the exponent of 5. So, there are 232=12 factors. This means there are 122=6 paris that multiply to 90, and their products together is 906, so the answer is k=6.

Hoping this helped, 

asdf334

 Mar 23, 2019

0 Online Users