Solution 2.2:5b

From Förberedande kurs i matematik 1

Because the straight line is to have a slope of −3, its equation can be written as

y=−3x+m

where m is a constant. If the line is also to pass through the point (x,y) = (1,-2), the point must satisfy the equation of the line,

−2=−31+m

which gives that m=1.

The answer is thus that the equation of the line is y=−3x+1.