7) To write the equation of the line that passes through (-1, -4) with a slope of -1
First find the intercpet
To do that, substitute x = -1 , y = -4 and m=1 /3
into y= mx + b and then solve for b
-4 = (1/3) (-1) + b
-4 = -1/3 + b
add 1/3 to both-side of the equation
-4 + 1/3 = b
-12+1 / 3 = b
-11/3 = b
b = -11/3
To form equation of the line, simply substitute m=1/3 and b= -11/3 into y=mx + b
y = 1/3 x - 11/3
8) slope (m) = -1 x= -5 and y = 2
substitute into y=mx + b and then solve for b
2 = -1(-5) + b
2 = 5 + b
subtract 5 from both-side of the equation
2- 5 = b
-3 = b
To form the new equation
substitute m = -1 and b = -3 into y=mx + b
That is;
y = -1x - 3
y = -x - 3