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if the zeroes of x2-kx+6 are …

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if the zeroes of x2-kx+6 are in the ratio 3:2, find k.

  • 1 answers

Payal Singh 8 years, 3 months ago

Let roots are {tex}\alpha \ and \ \beta {/tex}

{tex}{\alpha \over \beta } = {3\over 2}{/tex}

=> {tex}\alpha ={ 3\over 2}\beta{/tex}.....(1)

Then

Product of roots = {tex}c\over a{/tex}

=> {tex}\alpha \beta = 6{/tex}

=> {tex}{3\over 2}\beta \beta = 6{/tex}

=> {tex}\beta^2 = 4{/tex}

=> {tex}\beta = \pm 2{/tex}

Putting in (1) we get

{tex}\alpha = \pm 3{/tex}

Now sum of roots = {tex}-{b\over a}{/tex}

=> 3 + 2 = k    or -3 + (-2) = k 

=> k = 5   or k = -5

 

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