Define the variables: x = weeks elapsed, y = plant’s height in inches
Rate: 2 inches per week
Write the equation: y=2x+6
Solve the equation:
Input y=36 since we must find the time it takes the plant to grow to 36 inches, and recall that our variable y is the plant’s height based on x (number of weeks elapsed):
(36)=2x+6
Solve for x: subtract 6 from both sides:
36-6=2x
Simplify and solve for x: divide both sides by 2:
30/2=x
Simplify:
x=15
Remember that x is the number of weeks elapsed, so the plant would take 14 weeks to grow to a height of 36 inches. Let’s input x=15 back into the function to make sure it satisfies it:
36=2(15)+6
36=30+6
36=36
Therefore, your answer is: it takes 15 weeks for the plant to grow to 36 inches tall.