Điều kiện xác định: H≠−1H≠−1

    −4,9H2+15,2H+20,1H+1−4,9H2+15,2H+20,1H+1

=−4,9H2−4,9H+15,2H+20,1H+1=−4,9H2−4,9H+15,2H+20,1H+1

=−4,9H(H+1)+15,2(H+1)H+1=−4,9H(H+1)+15,2(H+1)H+1

=(H+1)(15,2−4,9H)H+1=(H+1)(15,2−4,9H)H+1

=15,2−4,9H

Điều kiện xác định: \(H\ne-1\)

    \(\dfrac{-4,9H^2+15,2H+20,1}{H+1}\)

\(=\dfrac{-4,9H^2-4,9H+15,2H+20,1}{H+1}\)

\(=\dfrac{-4,9H\left(H+1\right)+15,2\left(H+1\right)}{H+1}\)

\(=\dfrac{\left(H+1\right)\left(15,2-4,9H\right)}{H+1}\)

\(=15,2-4,9H\)

Điều kiện xác định: \(H\ne-1\)\(\dfrac{-4,9H^2+15,2H+20,1}{H+1}=\dfrac{-4,9H^2-4,9H+20,1H+20,1}{H+1}=\dfrac{-4,9H\left(H+1\right)+20,1\left(H+1\right)}{H+1}=\dfrac{\left(H+1\right)\left(20,1-4,9H\right)}{H+1}=20,1-4,9H\)