There are four required questions in senior high school mathematics. It is known that A = (2, 1) and B = (3, λ). If (2a-b)⊥b, what is the value of λ?
2a-b=(2*2， 1*2)-(3，λ)
=(4-3,2-λ)=( 1,2-λ)
Because (2a-b)⊥b
Then 1*3+(2-λ)*λ=0.
λ^2-2λ-3=0
(λ-3)(λ+ 1)=0
λ=3 or λ=- 1