Hey this is probably really simple but I can't get my head around it.

1) Find the possible values ofafor which y =ax+1 is a tangent to y = 3x²-4x+4

2)Find the possible values ofkfor which y =x-8 is a tangent to y= 4x²+kx+ 1

Would be really grateful if someone could just get me started and explain what to do. Thanks