Write a Linear Equation from a Graph

Write an equation that represents the graphed line.

• y = 2x + 1

• y = -2x + 1

• y = -2x

• y = 2x - 1

Answer explanation

Start by identifying where the graphed line crosses the y-axis - this is the "b" or "begin" value of the graph, b = 1. Next, determine the slope or "move" value between 2 points. Here the move value is up 2 left 1, making the slope value -2/1 or m = -2. The equation is y = -2x +1.

Tags

8.F.4

Write an equation that represents the graphed line.

• y = x

• y = -x + 2

• y = -2x - 2

• y = x - 2

Tags

8.F.4

Interpret the slope of the graphed line. Choose the best answer.

• m = -2. The temperature rises 2 degrees for every 1 hour that passes.

• m = -2. Time decreases by 1 hour for every 2 degrees of temperature change.

• m = -2. The temperature decreases 2 degrees for every 1 hour that passes.

• m = -2. Time increases 1 hour for every 2 degrees of temperature increase.

Answer explanation

Since the slope is -2, we can rewrite it as -2/1 using an invisible 1 in the denominator. This gives us a ratio of change in y to change in x and shows us that the change in y (temperature) decreases by 2 degrees each time the change in x (time) increases by 1 hour.

Identify the slope and y-intercept of the graphed line. Choose the correct combination.

• m = -2, b = 1

• m = -1/2, b = 1

• m = 12.b = 2

• m = 1, b = 2

Write an equation for the graphed line in slope-intercept form. Use no spaces in your answer.

Choose the correct interpretation(s) about the graph. Choose all that apply.

• As x increases by 1, y increases by 2.

• As y decreases by 2, x increases by 1.

• As x increases by 2, y decreases by 4.

• As y decreases by 2, x decreases by 4.

This graph shows how the total amount of paper Dan's office has recycled depends on the number of weeks since they started the new recycling plan.

Identify the slope of the graphed line and interpret its meaning.

• m = 1/8. Dan's office recycles 1 kg of paper every 8 weeks.

• m = -8. Dan's office recycles -8 kg of paper every 1 week.

• m = -1/8. Dan's office recycles -1 kg of paper every 8 weeks.

• m = 8. Dan's office recycles 8 kg of paper every 1 week.

Answer explanation

Since slope values are a ratio of change in y (kg) to change in x (time in weeks), the slope represents kg per week.

Write an equation for the graphed line. Use y = mx + b format, no spaces in your answer.