# If x=-2 a solution of the quadratic equation x2-2x 8=0

2
by jharna
x^2 - 2x +8  or  -8?

2015-12-03T16:54:49+05:30
Yes it is true -4-4+8 = 0
if one root of the qe  x^2-11x+k=0 is 9 find the value of k
this is d given question
yes i understood this but the above actual question
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2015-12-03T17:38:09+05:30
Question : Is x=-2, a solution of the quadratic equation  x² - 2x +8 = 0
⇒(-2)² - 2(-2) + 8 = 0
⇒ 4 - (-4) + 8 = 0
⇒4+4 + 8 = 0
⇒16 is not equal to 0
Therefore it is not a root of the given eq

If the given eq is x² - 2x - 8  then the solution is
x = -2
⇒(-2)² - 2(-2) - 8 = 0
⇒4- (-4) - 8 = 0
⇒4+4 - 8 = 0
⇒8 - 8 = 0
⇒0=0
Therefore  -2 is a root of the given eq

Roots are 5, -4
yeah
This means that x= 5,   x= -4 ;  the factors are (x-5) and (x+4)         Therefore the Q.E =      (x-5)(x+4)=0 ;     x^2 + 4x - 5x - 20;     x^2 - x - 20.     Therefor ethe Q.E = x^2 - x - 20
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if you understand it very well then thank you , and welcome