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Irina-Kira [14]
3 years ago
13

The seventh term of an arithmetic sequence is 21, and the tenth term is 126. The first term is _____..

Mathematics
2 answers:
garri49 [273]3 years ago
7 0
Pretend that the first term is 21, and the fourth term is 126 
<span>it's the same thing. </span>
<span>126 =21 +3d </span>
<span>105=3d </span>
<span>d=35 </span>
<span>21 =a1 +6(35) </span>
<span>21=a1 +210 </span>
<span>a1=-189</span>
Ivan3 years ago
7 0
a_7=21;\ a_{10}=126\\\\a_{10}-a_7=3d\\\\subtitute\\\\3d=126-21\\3d=105\ \ \ |divide\ both\ sides\ by\ 3\\d=35\\\\a_1=a_7-6d\\\\a_1=21-6\cdot35=21-210=-189\\\\Answer:\boxed{a_1=-189}
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5m³ + 2m - 7m³ - 8m

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2 years ago
A water tank is being filled by pumps at a constant rate. The volume of water in the tank V, in gallons, is given by the equatio
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7 0
2 years ago
60 books represent 1 percent of the total books in the library 3
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8 0
3 years ago
Example 2
Arada [10]

Answer:

y=x-2

Step-by-step explanation:

If you have drawn the graph of y = x^2 - 3x + 1.

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The equation of the line which should be drawn is: y=x-2

What this means is simply:

If

y = x^2 - 3x + 1$ and $y=x-2,$ then:\\x^2 - 3x + 1=x-2\\x^2 - 3x + 1-x+2=0\\x^2 - 4x + 3=0

5 0
3 years ago
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