\(f\left(x\right)=2x^2-3x+1.\)
\(f\left(x\right)=2x^2-2x-x+1\)
\(f\left(x\right)=\left(2x^2-2x\right)-\left(x-1\right)\)
\(f\left(x\right)=2x.\left(x-1\right)-\left(x-1\right)\)
\(f\left(x\right)=\left(x-1\right).\left(2x-1\right)\)
+ Thay \(x=-1\) vào \(f\left(x\right)\) ta được:
\(f\left(-1\right)=\left[\left(-1\right)-1\right].\left[2.\left(-1\right)-1\right]\)
\(f\left(-1\right)=\left(-2\right).\left(-3\right)\)
\(f\left(-1\right)=6.\)
+ Thay \(x=2\) vào \(f\left(x\right)\) ta được:
\(f\left(2\right)=\left(2-1\right).\left(2.2-1\right)\)
\(f\left(2\right)=1.3\)
\(f\left(2\right)=3.\)
+ Thay \(x=-\frac{1}{2}\) vào \(f\left(x\right)\) ta được:
\(f\left(-\frac{1}{2}\right)=\left[\left(-\frac{1}{2}\right)-1\right].\left[2.\left(-\frac{1}{2}\right)-1\right]\)
\(f\left(-\frac{1}{2}\right)=\left(-\frac{3}{2}\right).\left(-2\right)\)
\(f\left(-\frac{1}{2}\right)=3.\)
Chúc bạn học tốt!
