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f-x-2-4f-x-8x-2-32x-28-f-x-




Question Number 205825 by tri26112004 last updated on 31/Mar/24
[f′(x)]^2 +4f(x)=8x^2 −32x+28  ⇒f(x)=¿
[f(x)]2+4f(x)=8x232x+28f(x)=¿
Commented by mr W last updated on 31/Mar/24
f(x)=x^2 −4x+3  or  f(x)=−2x^2 +8x−9  or ...
f(x)=x24x+3orf(x)=2x2+8x9or
Answered by MM42 last updated on 31/Mar/24
f=ax^2 +bx+c⇒f′=2ax+b  ⇒4a^2 x^2 +4abx+b^2 +4ax^2 +4bx+4c=8x^2 −32x+28  ⇒4a^2 +4a=8⇒a=1 or a=−2  4ab+4b=−32  &  b^2 +4c=28  if a=1⇒b=−4 & c=3  ⇒f(x)=x^2 −4x+3  ✓  if a=−2⇒b=8 & c=−9  ⇒f(x)=−2x^2 +8x−9  ✓
f=ax2+bx+cf=2ax+b4a2x2+4abx+b2+4ax2+4bx+4c=8x232x+284a2+4a=8a=1ora=24ab+4b=32&b2+4c=28ifa=1b=4&c=3f(x)=x24x+3ifa=2b=8&c=9f(x)=2x2+8x9

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