Question

xác định công thức của hàm số y=f(x) biết: f(a-1)=1/2(a²-3a+11/2)

Answer 1

\(f\left(a-1\right)=\dfrac{1}{2}\left(a^2-3a+\dfrac{11}{2}\right)\)

=>\(f\left(a-1\right)=\dfrac{1}{2}\left(a^2-3a+2+\dfrac{7}{2}\right)\)

\(\Leftrightarrow f\left(a-1\right)=\dfrac{1}{2}\left(a-1\right)\left(a-2\right)+\dfrac{7}{4}\)

=>\(f\left(a\right)=\dfrac{1}{2}\cdot a\cdot\left(a-1\right)+\dfrac{7}{4}\)

\(\Leftrightarrow f\left(a\right)=\dfrac{1}{2}a^2-\dfrac{1}{2}a+\dfrac{7}{4}\)