Asecurity alarm requires a four-digit code. the code can use the digits 0–9 and the digits cannot be repeated. which expression can be used to determine the probability of the alarm code beginning with a number greater than 7?

Step-by-step explanation:

We have total of 10 digits from 0 to 9

We need a four digit code and beginning with a number greater than 7

We have 2 choices for number greater than 7

For first digit we have 2 choices

Now, we are left with 9 choices because one is filled and digits should not repeat.

For second digit we have 9 choices

For third digit we will have 8 choices

And for fourth digit we will have 7 choices

Total number of choices are

using

Cancel common terms from numerator and denominator we get:

.

(w – 2.5)(w + 2.5)

(–4v – 9)(–4v + 9)

step-by-step explanation: