Find the equation of the straight line passing trough the points (-2,1 ) and (1, 4).

Firstly you need to understand the question. It asks for the equation of a straight line, which is linear, thus of the form y = mx+c. Now, knowing that the equation is of that form we firstly need to find the gradient, which tells the steepness and the direction of the graph. The way to find this gradient is to subtract the two "y" values, and "x" values and divide the change in y by the change in x. So the y values are 1 and 4, thus the change in y is -3. The values of x are -2 and 1, thus the change in x is -3. Be careful to subtract the right way, the values of one point minus the values of the others. Now we can find the gradient by dividing the rates of change in y by x, which is 1. The equation looks like this : y=x+c. To find c we firstly need to choose a pair of coordinates to work with. In this example I will use (1, 4). This tells me that when x is 4 y is 1, thus by replacing these values in the equation we get that 4 = 1+c. This equation can be solved and the result of c is 3. Now we found the equation of the line which is y = x+3.