For which value of m does the graph of y = 18x2 + mx + 2 have exactly one x-intercept?

This will be a parabola which will just touch the x access and will be a perfect square The discrimant b^2 - 4ac  will be = 0 so we have

m^2 - 4*18*2 = 0
m^2 = 144

m  =  +/-12

so its m = 12 or -12