For the first digit of the required 20-digit number, we can have 9 choices for the number, those are the digits 1 to 9. In the second digit of the number, we will only have 8 choices. That is because, we don't want to write a number in the second digit that is similar to the first digit and the third digit.
Similarly, in the third digit's place, we will only have 8 choices because we do not want the digit to be similar to the second digit and the fourth digit. This will go on up until the 19th digit. In the 20th digit, we will also have 9 choices (from 0-9) but we do not want the digit to be similar to the 19th digit.
From the explanation given above, we have the number of ways,
n = 9 x 8^(19 - 1) x 9 = 1.459 x 10^18
<em>ANSWER: 1.459 x 10^18</em>
I think it’s 990 maybe not I did 1080/180=6 then 15*6=90 then did 1080-90=990 I think
Answer: x = - 12
8x + 45 = 10x + 69
⇔ 10x - 8x = 45 - 69
⇔ 2x = -24
⇔ x = -12
Step-by-step explanation:
Answer: the answers are 2,3,and 5
Step-by-step explanation:
Answer: 79
Concept:
Here, we need to understand the idea of evaluation.
When encountering questions that gave you an expression with variables, then stated: "If x = a, y = b, z = c" (a, b, c are all constants), this means you should substitute the value given for each variable back to the expression.
Solve:
<u>Given information</u>
10x² - 7x + 10
x = 3
<u>Substitute the value into the expression</u>
= 10 (3)² - 7 (3) + 10
<u>Simplify by multiplication</u>
= 10 (9) - 21 + 10
= 90 - 21 + 10
<u>Simplify by subtraction</u>
= 69 + 10
<u>Simplify by addition</u>
= 79
Hope this helps!! :)
Please let me know if you have any questions
