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in Quadratic Equations by (47.8k points)
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If one root of the equation 2x2 + px – 3 = 0 is – 3 then the value of p is 

(A) 3 

(B) 4 

(C) 5 

(D) 6

1 Answer

+1 vote
by (48.6k points)
edited by
 
Best answer

Correct option is (C) 5

Given Equation is:

\(2 x^2+p x-3=0\)

One root = -3

let the other root = \(\beta\)

\(\alpha \beta  =\frac{c}{a}\)

\(-3 \times \beta  =\frac{-3}{2}\)

\(-3 \beta  =\frac{-3}{2}\)

\(\beta  =\frac{-\not3}{2 \times -\not3}=\frac{1}{2}\)

\(\alpha+\beta  =-\frac{b}{a}\)

\(\frac{-3}{1}+\frac{1}{2}  =\frac{-p}{2}\)

\(-\frac{6+1}{2}  =-\frac{p}{2}\)

\(\not-\frac{5}{\not2}  =\not-\frac{p}{\not2}\)

\(\therefore p  =5\)

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