Hi there!
Let's first determine the x-intercept. When dealing with an x-intercept we must realise the y-coordinates equal 0.
[tex]y = - 2x - 21 \\ y = 0 \\ \\ - 2x - 21 = 0[/tex]
Add 21 to both sides.
[tex] - 2x = 21[/tex]
Divide both sides by -2.
[tex]x = \frac{21}{2} = 10 \frac{1}{2} [/tex]
Therefore, the x-intercept is the point (10 1/2; 0).
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Now let's continue with the y-intercept, which is easier. When dealing with an y-intercept we must realise the x-coordinates equal 0.
[tex]y = - 2x - 21 \\ x = 0 \\ \\ y = - 2 \times 0 - 21 = - 21[/tex]
Therefore, the y-intercept is the point (0; -21).
