Question 1003395
if i have a gradient and intercept for example Y= -3.1x-1.7 
how am i supposed to no how to plot this equation on a graph?
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You didn't show a gradient and intercept, you show an equation.
y = -3.2x - 1.7
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Pick 2 values for x and find y.
Plot the 2 points, draw a line thru them.