Arun
Last Activity: 5 Years ago
- d> 0: 2 distinct real roots: factors over the reals
- d
- d = 0: 1 real root with 2: factors over the reals as a square.
Here d=b^2–4ac as given equation is having two roots we follow above rules , First we need to know the basics before solving this question
Given range -1m values can be (0,1,2)
Given Equation x^2–2mx-1=0
We need to prove that x values lies in between (-2,4)=====> This means x values can be (-1,0,1,2,3) and they can be complex roots also
x^2–2mx-1=0….substitute m=0 then
x^2–2(0)(x)-1=0
x^2=1
x=1 or x=-1 ====> It satisfies the given range
now substitute m=1, Then
x^2–2(1)x-1=0
x^2–2x-1=0
to find roots use this formulae -b+-suart(b^2–4ac)/2*a=====>
2+squart(8)/2 and 2-squart(8)/2 ==> 2(1+squart(2))/2 and 2(1-squart(2))/2
On simpler calculation we get roots as 1+squrt(2),1-squrt(2) This lies in the above mentioned range of x(-1,0,1,2,3)
Now substitute m=2,Then
x^2–2(2)x-1=0
x^2–4x-1=0
Again to find roots use the same formulae -b+-suart(b^2–4ac)/2*a
2+squart(20)/2 and 2-squart(20)/2 ====> 2(1+squart(5))/2 and 2(1-squart(5))/2
so roots are 1+squart(5) and 1-squart(5) ===> This satisfies the desired range but one of the root is not satisfied as the value is just above 3
Note : Here to find roots i used formaule -b+-squart(b^2–4ac)/2*a
where b^2–4ac=discriminant