السؤال
الحل
f ( x ) = x x + 1 g ( x ) = x 2 − 1
( f + g ) ( x ) = f ( x ) + g ( x ) = x x + 1 + x 2 − 1
المجال: { x ∣ x ≠ − 1 , x ∈ R }
( f − g ) ( x ) = f ( x ) − g ( x ) = x x + 1 − x 2 + 1
( f ⋅ g ) ( x ) = f ( x ) ⋅ g ( x ) = x x + 1 ⋅ ( x − 1 ) ( x + 1 ) = x ( x − 1 )
f g ( x ) = f ( x ) g ( x ) = x x + 1 ÷ ( x 2 − 1 ) = x x + 1 ⋅ 1 x 2 − 1
المجال: { x ∣ x ≠ − 1 , x ≠ 1 , x ∈ R }
1-،1-
0، غير معرفة.
4,2
f(x)=x2−2xg(x)=x+9
(f+g)(x)=f(x)+g(x)=x2−2x+x+9=x2−x+9
المجال: Rأو(−∞,∞)
(f−g)(x)=f(x)−g(x)=x2−2x−x−9=x2−3x−9
(f⋅g)(x)=f(x)⋅g(x)=(x2−2x)⋅(x+9)=x3+9x2−2x2−18x=x3+7x2−18x
fg(x)=f(x)g(x)=x2−2xx+9
المجال: {x∣x≠−9,x∈R}
f(x)=xx+1g(x)=x2−1
(f+g)(x)=f(x)+g(x)=xx+1+x2−1
المجال: {x∣x≠−1,x∈R}
(f−g)(x)=f(x)−g(x)=xx+1−x2+1
(f⋅g)(x)=f(x)⋅g(x)=xx+1⋅(x−1)(x+1)=x(x−1)
fg(x)=f(x)g(x)=xx+1÷(x2−1)=xx+1⋅1x2−1
المجال: {x∣x≠−1,x≠1,x∈R}
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