Question 169636
let x be the number of rows and y be the number of trees in each row.
:
x*y=84...eq 1
x=y+5....eq 2
:
take x's value from eq 2 and plug it into eq 1
:
(y+5)y=84
:
{{{y^2+5y-84=0}}}
:
solve by quadratic formula y=7 and y =-12....throw out the negative value
:
using y's value in eq 2 we get:{{{highlight(x=7+5=12)}}}rows
:
*[invoke quadratic "y",1,5,-84]