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If F(X) = X2 − 3x + 4, Then Find the Values of X Satisfying the Equation F(X) = F(2x + 1). - Mathematics

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Question

If f(x) = x2 − 3x + 4, then find the values of x satisfying the equation f(x) = f(2x + 1).

 

Solution

Given:
f (x) = x2 – 3x + 4
Therefore,
(2x + 1) = (2x + 1)– 3(2x + 1) + 4
                = 4x2 + 1 + 4x – 6x – 3 + 4
                = 4x2 – 2x + 2
Now,
(x) = f (2x + 1)
⇒ x2 – 3x + 4 = 4x2 – 2x + 2
⇒ 4x2 – x2 – 2x + 3x + 2 – 4 = 0
⇒ 3x2 + x – 2 = 0
⇒ 3x2 + 3x – 2x – 2 = 0
⇒ 3x(x + 1) – 2(x +1) = 0
⇒ (3x – 2)(x +1) = 0
⇒ (x + 1) = 0  or  ( 3x – 2) = 0

\[\Rightarrow x = - 1 \text{ or }  x = \frac{2}{3}\]
Hence,
\[x = - 1, \frac{2}{3}\] 

 

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Chapter 3: Functions - Exercise 3.2 [Page 11]

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RD Sharma Mathematics [English] Class 11
Chapter 3 Functions
Exercise 3.2 | Q 1 | Page 11

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