The general equation of any line through (1,7) is:
\\y-7=m(x-1)\\y=mx+(7-m)
Sub into other function:
\\mx+(7-m)=2+5x-3x^2\\3x^2+(m-5)x+(5-m)=0
If the line is a tangent then the discriminant is equal to zero.
\\\Delta=0
Solve for m then go fuck bitches mmmkay.