we know that r=a +(/lambda b ). /lambda is a constant. the above is the ans given while the below is my working. my b1 and b2 is not the same with the ans. is the ans given acceptable ? (b1 and b2) here's only the partial working. i'm having problem with tht first part. accorfing to the ans given, the b1 and b2 are simplified . in this case, why the b1 and b2 can be simplified?

https://www.flickr.com/photos/123101...3/14283658984/

https://www.flickr.com/photos/123101...3/14097487299/

https://www.flickr.com/photos/123101...3/14097497469/

sorry i cant upload the photo directly, so i choose to upload it onto flickr