Question

The slope-intercept form of a line is y = mx + b, where m is the slope and b is the y-intercept. If Shawn knows that the slope of the line is 4 and the line passes through the point (1,-8), which equation should he use to find the y-intercept and what is the y-intercept of the line? Choices are as follows: b = y + mx b = y - mx b =
`(y-m)/(x)` b = -12 b = -4 b = 2

Answer 1

b=y-mx

Explanation:

• We know that y=mx+b is the slope intercept form of a line and we know that the slope of the line is 4.
• So:
• y = 4x+b
• However, we need to find the y intercept of the line which is b. Using the point (1,-8), we can find the y intercept.
• We need to find the equation to find the y-intercept.
• So:
• y = mx+b
• b=y-mx
• And now, we can substitute 4 for m which is the slope
• b=y-4x
• Using the point (1,-8) we can find the y-intercept
• b=(-8)-4(1)
• b=-8-4
• b=-12

the equation of the line is y = 4x - 12 with the slope being 4 and y-intercept is -12. The equation we used is b = y-mx