Question

Michael chose some positive number, multiplied it by itself, added 1, multiplied the result by 10, added 3, and multiplied the result by 4. His final answer was 2012. What number did Michael choose?

Answer 1

Answer: 7

Step-by-step explanation:

Let the number chosen by Michael be x.

We are told that he multiplied it by itself, added 1. This would be:

= = ( x × x) + 1 = x² + 1

We are further told that he multiplied the result by 10, and added 3. This would be:

= = [(x² + 1) × 10] + 3

= 10x² + 10 + 3

= 10x² + 13

Lastly, he multiplied the result by 4 and his final answer was 2012. This would be:

(10x² + 13) × 4 = 2012

40x² + 52 = 2012

40x² = 2012 - 52

40x² = 1960

x² = 1960/40

x² = 49

x = ✓49

x = 7

The number is 7

can be expressed as:

= ( x × x) + 1 = x² + 1