Question

If u = 2i – j; v = -5i + 4j and w = j find -2u. (v + w).

Answer 1

To find -2u. (v + w).

First replace the values and then use the order of operations:

-2u. (v + w)

-2(2i – j)(( -5i + 4j)+( j)=

-2(2i – j)(-5i +5j)

-4i +5j(-5i +5j)

20i² -20ij - 25ij + 25j²

20i² -45ij + 25j²