Question

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

Answer 1

Answer:

-40

Explanation:

Given

u = 2i - j; v= -5i + 4j and w = j

Required

4u(v-w)

4u = 4(2i) = 8i

v - w = -5i + 4j - j

v - w = -5i + 3j

Substitute

4u(v-w)

= 8i(-5i+3j)

= -40(i*i) [since i*i = 1]

= -40

Hence the required solution is -40