Question

the slope intercept form of a line is y = mx + b, plus b where m is the slope and b is the y-intercept. If Sean knows the slope of the line is 4 and the line passes through the point 1 and -8 which equation should he use to find the Y intercept and what is the y-intercept of the line?

Answer 1

The slope intercept form of equation is

Y = mx + b

where m = slope and b = intercept

Sean knows the slope to be 4

passes through the point 1 and -8

This implies that x = 1 and y =-8

slope = m = 4

(1, -8)

y - y1 = m(x - x1)

y - (-8) = 4(x - 1)

y + 8 = 4 * x - 4*1

y + 8 = 4x - 4

make y the subject of the formula

y = 4x - 4 - 8

y = 4x - 12

Since, y = mx + b

Therefore b = -12

The equation of the line is

y = 4x - 12

Intercept of the line is -2

The answer is y = 4x - 12 and -12