if p=12i-4j and q=-7i+8j calculate the value of each expression below without a calculator. Estimate any irrational answers to one decimal place.

1.) p-2q 2.)||p+q||

Question

if p=12i-4j and q=-7i+8j calculate the value of each expression below without a calculator. Estimate any irrational answers to one decimal place.

1.) p-2q                              2.)||p+q||

anonymous · Answer

Okay I got the first one, but I dont understand how to do absolute values...

stamp · Answer

I am going to use this form of vector notation. Have you seen it before?$$p=<12,-4>,\ q=<-7,8>$$1). p-2q$$2q=2<-7,8>=<-14,16>$$$$p-2q=<12,-4>-<-14,16>$$$$p-2q=<26,-20>$$

stamp · Answer

@natnatwebb It is not absolute value, it is the magnitude of the vector. p+q has some direction <i,j> and you must find it's ||magnitude||

anonymous · Answer

isn't magnitude just $$\sqrt{i ^{2}+j ^{2}}$$

stamp · Answer

@natnatwebb Yes|dw:1361642136234:dw|

stamp · Answer

p+q = <5,4> ||<5,4>|| = sqrt(25+16) = sqrt(41)

anonymous · Answer

Yup okay see it now. It helps that it was magnitude and not absolute value! :) thanks a lot.