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f-2-x-2f-x-x-2-8x-15-f-x-




Question Number 195391 by mathlove last updated on 01/Aug/23
f^2 (x)+2f(x)=x^2 −8x+15  f(x)=?
f2(x)+2f(x)=x28x+15f(x)=?
Answered by MM42 last updated on 01/Aug/23
(f+1)^2 =x^2 −8x+16=(x−4)^2   ⇒f=∣x−4∣−1 ✓
(f+1)2=x28x+16=(x4)2f=∣x41
Answered by kapoorshah last updated on 01/Aug/23
let f(x) = ax + b  (ax + b)^2  + 2(ax + b) = x^2  − 8x +15  a^2 x^2  + 2abx + b^2  + 2ax + 2b = x^2  − 8x +15  a^2 x^2  + (2ab + 2a)x + b^2  + 2b = x^2  − 8x +15    a^2  = 1  a = 1                                     a = −1  2b + 2 = −8                      −2b −  2 = −8  b = −5                                 b = 3  ∴ f(x) = x − 5                ∴ f(x) = −x + 3
letf(x)=ax+b(ax+b)2+2(ax+b)=x28x+15a2x2+2abx+b2+2ax+2b=x28x+15a2x2+(2ab+2a)x+b2+2b=x28x+15a2=1a=1a=12b+2=82b2=8b=5b=3f(x)=x5f(x)=x+3

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