Answer:
The equation of the line is y = 4x
Step-by-step explanation:
* Lets revise how to form an equation of a line from its slope and
a point on the line
- The equation of a line is written as y = mx + b where m is the
slope of the line and b is the y-intercept.
- The line intersect the y-axis at point (0 , b)
* Lets solve the problem
- The line has slope = 4
- The line passes through the point (2 , 8)
∵ The slope = 4
∵ m is the slope of the line in the equation
∴ m = 4
- Substitute the value of m in the equation
∵ y = mx + b
∴ y = 4x + b
- To find the value of b substitute the x-coordinate and the
y-coordinate of the point instead of x and y of the equation
∵ The point (2 , 8) lies on the line
∵ y = 4x + b
- Put x = 2 and y = 8 in the equation to find b
∴ 8 = 4(2) + b ⇒ simplify
∴ 8 = 8 + b ⇒ subtract 8 from both sides
∴ 0 = b
- That means the y-intercept = 0 and the line passing through
the origin point
∴ y = 4x + 0
* The equation of the line is y = 4x
