Gram-Schmidt: Vektor

Question

1. Use Gram-Schmidt to construct an orthonormal pair q1 and q2 from a1 = (4, 5, 2, 2) and a2 = (1, 2, 0, 0). Express a1 and a2 as combinations of q1 and q2 and write down the triangular R in A = QR.

Die Lösung ist:

q2 = a2- (<a1,a2>/IIa1II)a1 = (1,2,0,0) - (14/7)  (4,5,2,2)

Wie kommt man auf die - 14? Ich verstehe den Term: <a1,a2> nicht...