"the argument" of a function, is simply "the expression being evaluated by that function".
[tex]\bf a)\qquad (x+2)^3\impliedby \stackrel{function}{(\qquad )^3}\qquad \stackrel{argument}{x+2}
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b)\qquad f(2x-1)\impliedby \stackrel{function}{f(\qquad )}\qquad \stackrel{argument}{2x-1}
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c)\qquad \sqrt{x^2+4}\qquad \stackrel{function}{\sqrt{\qquad }}\qquad \stackrel{argument}{x^2+4}
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d)\qquad sin(5x)\impliedby \stackrel{function}{sin(\qquad )}\qquad \stackrel{argument}{5x}[/tex]
