Đáp án:
\(\begin{array}{l}
B5:\\
a.f\left( x \right) = 5{x^2} - 6x + 1\\
g\left( x \right) = - 6{x^2} + 7x - 8
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
B5:\\
a.f\left( x \right) = 5{x^2} - 6x + 1\\
g\left( x \right) = - 6{x^2} + 7x - 8\\
b.f\left( x \right) + g\left( x \right) = 5{x^2} - 6x + 1 - 6{x^2} + 7x - 8\\
= - {x^2} + x - 7\\
f\left( x \right) - g\left( x \right) = 5{x^2} - 6x + 1 + 6{x^2} - 7x + 8\\
= 11{x^2} - 13x + 9\\
B1:\\
a. - \dfrac{{54}}{{3.2}} - 5.2 = - \dfrac{{54}}{6} - 10\\
= - 9 - 10 = - 19
\end{array}\)