Answer:
John is 9, Brian is 6.
Step-by-step explanation:
I)
Let [tex]J[/tex] represent John's age and [tex]B[/tex] represent Brian's age.
John is three years older than Brian. In other words:
[tex]J=B+3[/tex]
The product of their ages is 54. Or:
[tex]JB=54[/tex]
II)
Write this as a quadratic by substituting:
[tex]JB=54\\(B+3)B=54\\B^2+3B-54=0[/tex]
III)
Solve the quadratic:
[tex]B^2+3B-54=0\\B^2-6B+9B-54=0\\B(B-6)+9(B-6)=0\\(B+9)(B-6)=0\\B=-9, 6[/tex]
Since age cannot be negative, Brian must be 6 years old right now.
John is three year older, so John is 9.
