calcule o 1 termo da p.a
a)razão r=3 sabendo que A7=21
b)em que a12=-29 e r=-4
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Boa noite Monah!
Solução!
![a)\\\\
a1=?\\\\
r=3\\\\
a7=21\\\\\\\\\
a7=a1+6r\\\\\
21=a1+6.3\\\\\
21=a1+18\\\\\
21-18=a1\\\\\
3=a1\\\\\
a1=3\\\\\\\\\\\\
b)\\\\
a1=?\\\\
r=-4\\\\
a12=-29\\\\\
a12=a1+11r\\\\
-29=a1+11(-4)\\\\
-29=a1-44\\\\
-29+44=a1\\\\
15=a1\\\\\
a1=15](https://tex.z-dn.net/?f=a%29%5C%5C%5C%5C%0Aa1%3D%3F%5C%5C%5C%5C%0Ar%3D3%5C%5C%5C%5C%0Aa7%3D21%5C%5C%5C%5C%5C%5C%5C%5C%5C%0Aa7%3Da1%2B6r%5C%5C%5C%5C%5C%0A21%3Da1%2B6.3%5C%5C%5C%5C%5C%0A21%3Da1%2B18%5C%5C%5C%5C%5C%0A21-18%3Da1%5C%5C%5C%5C%5C%0A3%3Da1%5C%5C%5C%5C%5C%0Aa1%3D3%5C%5C%5C%5C%5C%5C%5C%5C%5C%5C%5C%5C%0Ab%29%5C%5C%5C%5C%0Aa1%3D%3F%5C%5C%5C%5C%0Ar%3D-4%5C%5C%5C%5C%0Aa12%3D-29%5C%5C%5C%5C%5C%0Aa12%3Da1%2B11r%5C%5C%5C%5C%0A-29%3Da1%2B11%28-4%29%5C%5C%5C%5C%0A-29%3Da1-44%5C%5C%5C%5C%0A-29%2B44%3Da1%5C%5C%5C%5C%0A15%3Da1%5C%5C%5C%5C%5C%0Aa1%3D15%0A%0A "a)\\\\
a1=?\\\\
r=3\\\\
a7=21\\\\\\\\\
a7=a1+6r\\\\\
21=a1+6.3\\\\\
21=a1+18\\\\\
21-18=a1\\\\\
3=a1\\\\\
a1=3\\\\\\\\\\\\
b)\\\\
a1=?\\\\
r=-4\\\\
a12=-29\\\\\
a12=a1+11r\\\\
-29=a1+11(-4)\\\\
-29=a1-44\\\\
-29+44=a1\\\\
15=a1\\\\\
a1=15")
Boa noite!
Bons estudos!
Solução!
Boa noite!
Bons estudos!
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