Let f,g : R→R be defined respectively by f(x)=x+1,g(x)=2x−3. Find f+g,f−g and fg
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Solution
f,g:R→R is defined as f(x)=x+1 g(x)=2x−3 Now, (f+g)(x)=f(x)+g(x)=(x+1)+(2x−3)=3x−2 ∴(f+g)(x)=3x−2 Now, (f−g)(x)=f(x)−g(x)=(x+1)−(2x−3)=x+1−2x+3=−x+4 ∴(f−g)(x)=−x+4 (fg)(x)=f(x)g(x),g(x)≠0,x∈R ∴(fg)(x)=x+12x−3,2x−3≠0or2x≠3 ∴(fg)(x)=x+12x−3,x≠32