Question

Se considera functia f : R - R, f(x) = -2x+1
Determinati numarul real m, stiind ca punctul A(m,-7) se afla pe graficul functiei f.

Answer 1

A(m,-7) ∈ Gf ⇔F(m)=-7 ⇔ -2m+1=-7 ⇔2m-1=7 ⇔2m=8 ⇔m=4

Answer 2

$\rm f \in \mathbb R \longrightarrow \mathbb R;~f(x)=1-2x \\ \\ A(m;-7) \in G_f \longrightarrow f(m)=-7 \\ \\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~f(m)=1-2m \\ \\ 1-2m=-7 \\ \\ -2m=-8|:(-2) \\ \\ \bold{m=4}$