y=5+3x

its a linear equation so it will give a straight line.

Take any 3 points that satisfy the equation like (0,5),(1,8) etc.plot them on graph and join them and extend the segment obtained from both sides

2)second equation is of parabola.

Find points where y=0.these two will lie on x axis.add them and divide it by 2 to get a third point.put this value in equation to get a particular point on y axis.now draw a rough sketch passing through these 3 points such that it make a U (distance between papallel lines will keep on increasing).I am giving a rough sketch so that you could check your result.