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Find the value. Of a and …

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Find the value. Of a and b for which..x=3/4 and x=2 are the zeroes of the polynomial p(x) = ax2 +bx -6
  • 1 answers

Sia ? 6 years, 7 months ago

We have the equation, 

{tex}ax^2+bx-6=0{/tex}

Putting x = {tex}\frac{3}{4}{/tex} , we get
{tex}\therefore{/tex} a({tex}\frac{3}{4}{/tex})2 + b({tex}\frac{3}{4}{/tex}) - 6 = 0

 {tex}\Rightarrow{/tex} a{tex}\frac{9}{16}{/tex} +b({tex}\frac{3}{4}{/tex}) - 6 = 0
{tex}\Rightarrow{/tex} 9a + 12b - 96 = 0
{tex}\Rightarrow{/tex} 3a + 4b = 32 ..(i)
Putting x = -2, we get
a(-2)2 + b(-2) - 6 = 0
4a -2b = 6
2a - b = 3 ..... (ii)
Multiplying (ii) by 4 adding the result from (i), we get
11a = 44 {tex}\Rightarrow{/tex} a = 4
Putting a = 4 in (i) , we get
3(4) + 4b = 32

{tex}\Rightarrow{/tex} 4b = 32 - 12 

 {tex}\Rightarrow{/tex} b = {tex}\frac{20}{4}{/tex} = 5
Therefore, the required value of a = 4 and b = 5.

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