The explicit formula for a arithmetic sequence is a_n = a_1 + (n - 1)d.
We want to find a_21.
a_21 = 17 + (21 - 1)(10)
a_21 = 17 + (20)(10)
a_21 = 17 + 200
a_21 = 217
The 21st term is 217.
H words * 1 hour = h words
3 hours 60 minutes 180 minutes
or h/180 words per minute
First find the slope.
-6--2=-4
-2--1=-1
The slope is -4/-1 or 4.
Now plug in one point and the slope into point slope
y-y1=m(x-x1)
y+2=4(x+1)
{-2x + 7y = -5
{-2x - 4y = 6 | · (-1)
{-2x + 7y = -5
{2x + 4y = -6 (+)
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-2x + 2x + 7y + 4y = -5 + (-6)
11y = -11 | : 11
y = -1
{y = -1
{2x + 4y = -6
{y = -1
{2x + 4 · (-1) = -6
{y = -1
{2x - 4 = -6 | + 4
{y = -1
{2x = -2 | : 2
{y = -1
{x = -1
2)) answer is 73
4)) answer is 5(x + 2)
