Question 453386
complete the square
(x-1/4)^2=169/4

factor
factors of -42 which add up to -1
-7 and 6
2x^2+6x-7x-21=0
2x*(x+3)-7*(x+3)=0

(x+3)*(2x-7) = 0

quadratic formula*[invoke quadratic "x", 2, -1, -21 ]