Steply

Graph y <= 1/2x + 1

Step by step, with the reason for every step · Graphing inequalities · Algebra 1

Step by step

The question

Question: graph y ≤ (1/2)x + 1.

y ≤ 12x + 1

The answer is not one point.

It is every point that makes this true.

That is a whole part of the grid.

answer = all the points that work

1 Draw the line

First we draw the line where both sides are equal: y = (1/2)x + 1.

y = 12x + 1

The sign has "or equal to".

So points on the line are answers too.

We draw it solid, like the filled circle on a number line.

≤ → solid line

Draw the grid.

The x-axis goes across.

The y-axis goes up and down.

They meet at 0.

That point is called the origin.

b = 1.

Start on the y-axis at 1.

m = 1/2.

Go right 2,

then up 1.

Dot.

Join the dots: solid.

2 Test a point

The line cuts the grid in two sides.

One side is the answer.

We test one point: (0, 0).

Zeros are easy to work with.

Put x = 0 and y = 0 in.

0 ≤ 12(0) + 1
0 ≤ 1 true

Is 0 less than or equal to 1?

Yes, that is true.

So (0, 0) is an answer.

3 Shade

So we shade the side with (0, 0).

Every point there is an answer.

4 Check

Let's check with a point in the shaded part: (−2, −1).

Put x = −2 and y = −1 in.

−1 ≤ 12(−2) + 1
−1 ≤ 0 true

True!

So the shading is right.

Let's look back.

First: draw the line.

Then: test a point.

Then: shade.

Last: check.

Answer
0 ≤ 1 true

Your turn

Try this one yourself, then check:

y ≤ 12x + 4
Show the answer
solid line y = x/2 + 4, shade below

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