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  • Which of the following equations has 2 as a root ? (A)x^{2}-4x+5=0\\ (B)x^{2}+3x-12=0\\ (C)2x^{2}-7x+6=0\\ (D)3x^{2}-6x-2=0

Which of the following equations has 2 as a root ?   

\\(A)x^{2}-4x+5=0\\ (B)x^{2}+3x-12=0\\ (C)2x^{2}-7x+6=0\\ (D)3x^{2}-6x-2=0

Answers (1)

(C)(C)2x^{2}-7x+6=0

Solution

            (A)      x^{2}-4x+5=0                       

            Put       x = 2

                        (2)^{2}-4(2)+5=0\\ 4-8+5=0\\ 9-8=0\\ 1 \neq 0
(B)

     x^{2}+3x-12=0\\ put\;\;x=2\\ (2)^{2}+3(2)-12=0\\ 4+6-12=0\\ 10-12=0\\ -2\neq0        

(C)
                  2x^{2}-7x+6=0\\ put\;\;x=2\\ 2(2)^{2}-7(2)+6=0\\ 8-14+6=0\\ 14-14=0\\ 0= 0

(D)    

                3x^{2}-6x-2=0\\ put\;\;x=2\\ 3(2)^{2}-6(2)-2=0\\ 12-12-2=0\\ -2\neq 0    

        Hence option (C) is only satisfy x = 2.

            Hence C has 2 as a root.

Posted by

infoexpert24

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