Step-by-step explanation
The factorial of an integer is given by the product of all the integers that are equal or smaller than it. For example, the factorial of 4 is:
![4!=1\cdot2\cdot3\cdot4](https://img.qammunity.org/2023/formulas/mathematics/college/xv1e9o5o7ttevy0z00pincjivw8pridv2c.png)
We must find the value of the following expression with factorials:
![(4!\cdot6!)/(2!\cdot5!)](https://img.qammunity.org/2023/formulas/mathematics/college/zj2mankegfwodht1r6acwcri68hifufsql.png)
The first thing that we can do is expand the four factorials in the expression:
![(4!\cdot6!)/(2!\cdot5!)=(1\cdot2\cdot3\cdot4\cdot1\cdot2\cdot3\cdot4\cdot5\cdot6)/(1\cdot2\cdot1\cdot2\cdot3\cdot4\cdot5)](https://img.qammunity.org/2023/formulas/mathematics/college/k7zgkqa0v5w3oaqt61g0e0lde4h53g10yg.png)
All the numbers on both the numerator and the denominator are multiplying. This means that if a number appears in the numerator and in the denominator it can be simplified. For example 1 appears twice in the numerator and twice in the denominator so it can be simplified:
![(1\cdot2\cdot3\cdot4\cdot1\cdot2\cdot3\cdot4\cdot5\cdot6)/(1\cdot2\cdot1\cdot2\cdot3\cdot4\cdot5)=(1\cdot1)/(1\cdot1)\cdot(2\cdot3\cdot4\cdot2\cdot3\cdot4\cdot5\cdot6)/(2\cdot2\cdot3\cdot4\cdot5)=(2\cdot3\cdot4\cdot2\cdot3\cdot4\cdot5\cdot6)/(2\cdot2\cdot3\cdot4\cdot5)](https://img.qammunity.org/2023/formulas/mathematics/college/mhsjswvwjwj07ug0n6xkkmge541xnx7qck.png)
2 appears twice in both the numerator and the denominator so it can be simplified:
![(2\cdot3\cdot4\cdot2\cdot3\cdot4\cdot5\cdot6)/(2\cdot2\cdot3\cdot4\cdot5)=(3\cdot4\cdot3\cdot4\cdot5\cdot6)/(3\cdot4\cdot5)](https://img.qammunity.org/2023/formulas/mathematics/college/hgyo99a79hn9f7pc7qhly970d6fs1cw5jz.png)
We have a 3, a 4 and a 5 in the denominator so we can simplify them with a 3, a 4 and a 5 of the numerator:
![(3\cdot4\cdot3\cdot4\cdot5\cdot6)/(3\cdot4\cdot5)=(3\cdot4\cdot5)/(3\cdot4\cdot5)\cdot(3\cdot4\cdot6)/(1)=3\cdot4\cdot6=72](https://img.qammunity.org/2023/formulas/mathematics/college/96oyb5qtluyxjri10ah1o3di3t5vt2aij6.png)
Answer
Then the answer is 72.