Question

if two roots of quadratic equation are 2 and 1then form quadratic equation

Answer 1

If x=a and x=b are the given roots of quadratic equation then equation is formed by formula

(x-a)(x-b)=0

now plug the given roots 2 and 1 into above formula

(x-2)(x-1)=0

simplify

$x^2-1x-2x+2=0$

$x^2-3x+2=0$

hence final answer is $x^2-3x+2=0$.

Answer 2

for this we adopt the formula
when both roots are positive
let one root be α and another be β
general form for it is
x²-(α+β)x+αβ
x²-(1+2)x+1*2
=x²-3x+2

or else....another way
x=2 and x=1
so x-2=0 and x-1=0
by zero product rule
(x-2)(x-1)=0
=>x²-3x+2=0