✏️ Development:
⭐ Initially, we have to find the reason why it was -1.5:
[tex]\large {\text {$ \sf f (n+1) = -2 f(n) $}}[/tex]
➡️ Having n, then we'll find the value of n, then we'll replace it with the found result.
[tex]\large {\text {$ \sf f (x+1) = -2.x = -1,5 $}}[/tex]
⌛ So, we will have to find what x is worth in this case:
[tex]\large {\text {$ \sf f ( 0,75 +1 ) = -2 \cdot 0,75 $}}[/tex]
[tex]\large {\text {$ \sf f ( 0,75) = -1,5 $}}[/tex]
→ Knowing this...
[tex]\large {\text {$ \sf f ( 1,5 + 1 ) = -2 \cdot 1,5 $}}[/tex]
[tex]\large {\boxed {\boxed {\sf f ( 2,5 ) = -3 }}}[/tex] [tex]\checkmark[/tex]
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