Area = l•w
length= 2x+1 width= x
210 = (2x+1)(x)
distribute x
210 = 2x^2 + x
move 210 to other side
2x^2+x-210 = 0
factor the polynomial
(2^x2+21x)-(20x-210)=0
x(2x+21)-10(2x+21)=0
(x-10)(2x+21)=0
x=10, -21/2
measurements can’t be negative so x=10
the width is 10
the length is 2(10)+1=21