Question

fie punctele A(-1,2),B(-3,1) C(2,1) si M(a, b) un punct oarecare din plan. aflati coordonatele vectorului u.
a) u=MA+2MB-3MC​

Answer 1

MA=(xA-xM)i+(yA-yM)j=(-1-a)i+(2-b)j

MB=(xB-xM)i+(yB-yM)j=(-3-a)i+(1-b)j

MC=(xC-xM)i+(yC-yM)j=(2-a)i+(1-b)j

=>u=(-1-a)i+(2-b)j+(-6-2a)i+(2-2b)j-(6-3a)i-(3-3b)j

u=(-1-a-6-2a-6+3a)i+(2-b+2-2b-3+3b)j

u=-13i+1j=>u(-13,1)