Question

 Tìm hệ số a của đa thức: P( x ) = ax² + 2x + 1 biết rằng P(\(\frac{1}{2}\)) = 1

Answer 1

P(x) = ax² + 2x + 1

P(1/2) = 1 <=> a . (1/2)² + 2 . 1/2 + 1 = 1

                 <=> a . 1/4 + 1 + 1 = 1

                 <=> a . 1/4 = -1

                 <=> a = -4

Answer 2

Ta có : \(P\left(x\right)=ax+2x+1\)

\(P\left(\frac{1}{2}\right)=a.\left(\frac{1}{2}\right)^2+2\left(\frac{1}{2}\right)+1=1\)

\(\frac{a}{4}+1=0\Leftrightarrow\frac{a}{4}=-1\Leftrightarrow a=-4\)

Answer 3

Ta có : \(P\left(x\right)=ax+2x+1\)

\(P\left(\frac{1}{2}\right)=a.\left(\frac{1}{2}\right)^2+2\left(\frac{1}{2}\right)+1=1\)

\(\frac{a}{4}+1=0\Leftrightarrow\frac{a}{4}=-1\Leftrightarrow a=-4\)