Need help with vectors q!Watch
The equation we have is.
a + lambda(-a + b) = (2/3)a + ub
a - lambda.a + lambda.b = (2/3)a + ub
a(1 - lambda - 2/3) + b(lambda - u) = 0
Now, since the rhs is zero, then so also is the lhs, which means that we must set the coefficients of a and b to zero.
Doing this gives us,
1 - lambda - 2/3 = 0
lambda - u = 0
1 - lambda = 2/3
lambda = u