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Gary draws this sequence of patterns of white and grey squares. The sequence is continued. How many grey squares will there be with 16 white squares?

Sagot :

Answer:

20 gray squares

Step-by-step explanation:

Given

See attachment for squares

Required

Number of gray squares when white = 16

First, we calculate the equation that represents both squares.

The white squares

[tex]a = 2[/tex] --- initial

[tex]d = 4 - 2 = 6 - 4[/tex]

[tex]d = 2[/tex] -- difference between successive gray squares

So, the nth term is:

[tex]W_n = a + (n - 1)d[/tex]

[tex]W_n = 2 + (n - 1)*2[/tex]

[tex]W_n = 2 + 2n - 2[/tex]

[tex]W_n = 2n[/tex]

The gray squares

[tex]a = 6[/tex] --- initial

[tex]d = 8-6=10-8[/tex]

[tex]d = 2[/tex] -- difference between successive gray squares

So, the nth term is:

[tex]G_n = a + (n - 1)d[/tex]

[tex]G_n = 6 + (n - 1) *2[/tex]

[tex]G_n = 6 + 2n - 2[/tex]

[tex]G_n = 4 + 2n[/tex]

When the white squares is 16

[tex]W_n = 16[/tex] --- Calculate n

[tex]W_n = 2n[/tex]

[tex]16 = 2n[/tex]

[tex]8 = n[/tex]

[tex]n = 8[/tex]

To get the number of gray squares;

Substitute [tex]n = 8[/tex] in [tex]G_n = 4 + 2n[/tex]

[tex]G_n = 4 + 2 * 8[/tex]

[tex]G_n = 20[/tex]

View image MrRoyal