If the vectors vecP=ahati+ahatj+3hatk"and"vecQ=ahati-2hatj-hatk are perpendicular to each other. Find the value of a ?

If the vectors vecP=ahati+ahatj+3hatk"and"vecQ=ahati-2hatj-hatk are pe

1.	If the vectors vecP=ahati+ahatj+3hatk"and"vecQ=ahati-2hatj-hatk are perpendicular to each other. Find the value of a ?
Answer» Solution :If VECTORS `vecP "and" vecQ` are perpendicular `RARR vecP.vecQ=0rArr (ahati + ahatj+3hatk).(ahati-2hatj-hatk)=0` `rArr a^(2)-2a-3=0rArra^(2)-3a+a-3=0rArra(a-3)+1(a-3)=0rArra=-1,3`