Notes
Operations of Functions
\((f+g)(x) = f(x) +g(x)\)
\((f-g)(x) = f(x) -g(x)\)
\((f \cdot g)(x) = f(x) ・ g(x)\)
\(\left(\frac{f}{g} \right)(x) = \displaystyle\frac{f(x)}{g(x)}\)
\((f \circ g)(x) = f(g(x))\)
Practice Problems
Let \(f(x)=5x+3,\,\, g(x)=3x+5,\,\, h(x)=x^2+10\)
\(\textbf{1)}\) \((f+g)(3)\) The answer is \(32\)
\(\textbf{2)}\) \((f-g)(4)\) The answer is \(6\)
\(\textbf{3)}\) \((f \cdot g)(-1)\) The answer is \(-4\)
\(\textbf{4)}\) \(\left(\frac{h}{f} \right)(3)\) The answer is \(\frac{19}{18}\)
\(\textbf{5)}\) \((f+h)(-1)\) The answer is \(9\)
Let \(f(x)=5x+3,\,\, g(x)=3x+5,\,\, h(x)=x^2+10\)
\(\textbf{6)}\) \((f-g)(x)\) The answer is \(2x-2\)
\(\textbf{7)}\) \((f \cdot g)(x)\) The answer is \(15x^2+34x+15\)
\(\textbf{8)}\) \(\left(\frac{f}{g} \right)(x)\) The answer is \(\frac{5x+3}{3x+5}, x\ne -\frac{5}{3}\)
\(\textbf{9)}\) \((g+h)(2x)\) The answer is \(4x^2+6x+15\)
\(\textbf{10)}\) \((f-g)(2x)\) The answer is \(4x-2\)
Let \(f(x)=5x+3,\,\, g(x)=3x+5,\,\, h(x)=x^2+10\)
\(\textbf{11)}\) \((f+g)(x)\) The answer is \(8x+8\)
\(\textbf{12)}\) \((f \cdot f)(x)\) The answer is \(25x^2+30x+9\)
\(\textbf{13)}\) \(\left(\frac{g}{f} \right)(x)\) The answer is \(\frac{3x+5}{5x+3}, x\ne -\frac{3}{5}\)
\(\textbf{14)}\) \((g \circ h)(x)\) The answer is \(3x^2+35\)
\(\textbf{15)}\) \((h \circ g)(x)\) The answer is \(9x^2+30x+35\)
