AI-তৈরি নমুনা উত্তর
দেওয়া আছে,
f ( x ) = x − 1 , x ≥ 1 f(x) = \sqrt{x - 1}, \quad x \ge 1 f ( x ) = x − 1 , x ≥ 1
g ( x ) = x 2 + 2 g(x) = x^2 + 2 g ( x ) = x 2 + 2
১ম অংশ: ( g ∘ f − 1 ) ( x ) (g \circ f^{-1})(x) ( g ∘ f − 1 ) ( x ) নির্ণয়:
ধরি, y = f ( x ) = x − 1 y = f(x) = \sqrt{x - 1} y = f ( x ) = x − 1
বা, y 2 = x − 1 y^2 = x - 1 y 2 = x − 1
বা, x = y 2 + 1 x = y^2 + 1 x = y 2 + 1
অতএব, f − 1 ( x ) = x 2 + 1 f^{-1}(x) = x^2 + 1 f − 1 ( x ) = x 2 + 1 , যেখানে x ≥ 0 x \ge 0 x ≥ 0 [যেহেতু f ( x ) ≥ 0 f(x) \ge 0 f ( x ) ≥ 0 ]
এখন,
( g ∘ f − 1 ) ( x ) = g ( f − 1 ( x ) ) = g ( x 2 + 1 ) (g \circ f^{-1})(x) = g(f^{-1}(x)) = g(x^2 + 1) ( g ∘ f − 1 ) ( x ) = g ( f − 1 ( x )) = g ( x 2 + 1 )
= ( x 2 + 1 ) 2 + 2 = (x^2 + 1)^2 + 2 = ( x 2 + 1 ) 2 + 2
= x 4 + 2 x 2 + 1 + 2 = x^4 + 2x^2 + 1 + 2 = x 4 + 2 x 2 + 1 + 2
= x 4 + 2 x 2 + 3 , ( x ≥ 0 ) = x^4 + 2x^2 + 3, \quad (x \ge 0) = x 4 + 2 x 2 + 3 , ( x ≥ 0 )
২য় অংশ: ( g ∘ f ) − 1 ( x ) (g \circ f)^{-1}(x) ( g ∘ f ) − 1 ( x ) নির্ণয়:
( g ∘ f ) ( x ) = g ( f ( x ) ) = g ( x − 1 ) (g \circ f)(x) = g(f(x)) = g(\sqrt{x - 1}) ( g ∘ f ) ( x ) = g ( f ( x )) = g ( x − 1 )
= ( x − 1 ) 2 + 2 = x − 1 + 2 = x + 1 , ( x ≥ 1 ) = (\sqrt{x - 1})^2 + 2 = x - 1 + 2 = x + 1, \quad (x \ge 1) = ( x − 1 ) 2 + 2 = x − 1 + 2 = x + 1 , ( x ≥ 1 )
ধরি, y = ( g ∘ f ) ( x ) = x + 1 y = (g \circ f)(x) = x + 1 y = ( g ∘ f ) ( x ) = x + 1
বা, x = y − 1 x = y - 1 x = y − 1
অতএব, ( g ∘ f ) − 1 ( x ) = x − 1 (g \circ f)^{-1}(x) = x - 1 ( g ∘ f ) − 1 ( x ) = x − 1 , যেখানে x ≥ 2 x \ge 2 x ≥ 2 [যেহেতু x ≥ 1 ⟹ x + 1 ≥ 2 x \ge 1 \implies x+1 \ge 2 x ≥ 1 ⟹ x + 1 ≥ 2 ]
উত্তর:
( g ∘ f − 1 ) ( x ) = x 4 + 2 x 2 + 3 ( x ≥ 0 ) (g \circ f^{-1})(x) = x^4 + 2x^2 + 3 \quad (x \ge 0) ( g ∘ f − 1 ) ( x ) = x 4 + 2 x 2 + 3 ( x ≥ 0 )
( g ∘ f ) − 1 ( x ) = x − 1 ( x ≥ 2 ) (g \circ f)^{-1}(x) = x - 1 \quad (x \ge 2) ( g ∘ f ) − 1 ( x ) = x − 1 ( x ≥ 2 )