Question

Alan thinks of a number. He squares it, then takes away 5, next multiplies it by 4, takes away 7, divides it by 3 and finally adds 6. His answer is 9. What number did Alan start with?

Answer 1

Answer:
`\pm3`

Explanation:

`[(4(x^(2) -5)-7)/3]+6=9`

`((4x^(2) -20)-7)/3=9-6`

`4x^(2) -27=3*3`

`4x^(2) =9+27`

`x^(2)=36/4=9`

`x=√(9) =\pm3`

`x = 3`