Notice that the 2 expressions have 2 common terms.
(r-s) is just (s-r) times (-1)
similarly
(t-s) is just (s-t) times (-1)
this means that :
(r-s) (t-s) + (s-r) (s-t)=-(s-r)[-(s-t)]+(s-r) (s-t)
the 2 minuses in the first multiplication cancel each other so we have:
-(s-r)[-(s-t)]+(s-r) (s-t)=(s-r) (s-t)+(s-r) (s-t)=2(s-r) (s-t)
Answer:
d)<span>2(s-r) (t-s) </span>
It depends on the question, but if the questions is sort of like "Person A and Person B shared 40 sweets in the ratio 3:5, how many sweets did Person A get" then you add 3 and 5 to get 8, and then you do 40 ÷ 8 to get 5 which is 1 in terms of the ratio. Then, you would multiply 5 by 3 to get 15 sweets. If it's a different type of question then let me know so I can help out :)
Basically, Justin and Tina's paths form two right-angled triangles whose hypotenuses(?) form a straight line between their end points. Therefore we need to find the two distances from the starting point and add them.
Justin walked 3 miles north and 6 miles west so his distance from the start is the square root of 9+36 or 45. This can be simplified to 3√5.
Tina walked 2 miles south and 4 miles east so her distance from the starting point is the square root of 4 + 16 or 20. This can be written as 2√5.
If we add these two distances together we get 5√5. Hence, Justin and Tina are 5√5 miles away from each other.
