$$ \text { Let } f(x)=a x^{2}+b x+c \text { be such that } f(1)=3, f(-2)=\lambda \text { and } $$ $f(3)=4$. If $f(0)+f(1)+f(-2)+f(3)=14$, then $\lambda$ is equal to :
Solution
<p>$f(1) = a + b + c = 3$ ..... (i)</p>
<p>$f(3) = 9a + 3b + c = 4$ .... (ii)</p>
<p>$f(0) + f(1) + f( - 2) + f(3) = 14$</p>
<p>OR $c + 3 + (4a - 2b + c) + 4 = 14$</p>
<p>OR $4a - 2b + 2c = 7$ ..... (iii)</p>
<p>From (i) and (ii) $8a + 2b = 1$ ..... (iv)</p>
<p>From (iii) $- (2) \times$ (i)</p>
<p>$\Rightarrow 2a - 4b = 1$ ..... (v)</p>
<p>From (iv) and (v) $a = {1 \over 6},\,b = {{ - 1} \over 6}$ and $c = 3$</p>
<p>$f( - 2) = 4a - 2b + c$</p>
<p>$= {4 \over 6} + {2 \over 6} + 3 = 4$</p>
About this question
Subject: Mathematics · Chapter: Sets, Relations and Functions · Topic: Sets and Operations
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