Line b is a direct variation.
Step-by-step explanation:
Here we have 4 lines a,b,c,d . We are required to answer direct variation i.e. lines for which values of y are changing for a single value of x ! Let perform vertical line test to check this.
Vertical line test Β means sketching various vertical lines in graph and if every vertical line cuts graph in only one point so it passes this test i.e. for every unique value of x there's only one value of y.
For line a:
Line a is line passing through point (0,1) which passes vertical line test.
For line b:
Line b is a vertical line which have many values of y for x=-4 which fails vertical line test and so it is a direct variation.
For line c & d:
Both of Lines c & d are parallel to each other and passes vertical line test.