RSA: How to compute plaintexts knowing ciphertexts, public key and relation between plaintexts I'm trying to solve an exercise where you have to compute two plaintexts $p_1$ and $p_2$, knowing the corresponding ciphertexts $c_1$ and $c_2$ and the public key, of which $e=3$, and $n$ is a large number. 
Also given is a relation between $p_1$ and $p_2$. $p_2 = c_1 \cdot p_1 + c_2$. Where $c_1$ and $c_2$ are constants.

I'm guessing I should use the fact that $e$ is a low number (3) since RSA is unsafe in this case. I'm not sure where to start, how should I go about solving this exercise?
Since this is an exercise, I'll provide the links of the articles as a hint;

The linearity of the messages  is first studied when $e=3$


Low-Exponent RSA with Related Messages by Don Coppersmith, Matthew Franklin, Jacques Patarin, Michael Reitert, EUROCRYPT 1996: Advances in Cryptology — EUROCRYPT ’96 pp 1-9


A more general case, where $e$ is not limited to 3 and the relation is linear is studied in


A New Related Message Attack on RSA Oded Yacobi and Yacov Yacobi, PKC 2005: Public Key Cryptography - PKC 2005 pp 1-8. 


It is quite clear that these attacks are related to textbook RSA and it must not be used in practice. 

For encryption, RSA has used either PKCS#1.5 padding or OAEP. Actually, we don't use RSA for encryption. We prefer it in digital signatures and that requires PSS padding or for Key Encapsulation, RSA-KEM.