Evaluate the dot product of (2,4) (-1,2)

6

Step-by-step explanation:

Given (x1, y1) and (x2, y2) dot product = (x1*x2 + y1*y2)

SO... given (2, 4) and (-1, 2) dot product = (2*-1 + 4*2)

= -2 + 8

= 6

x = ± 6i

step-by-step explanation:

x^2 = -36

take the square root of each side

sqrt(x^2) = sqrt(-36)

we know sqrt(ab) = sqrt(a) sqrt(b)

x = ±sqrt(36) sqrt(-1)

we know that sqrt (-1) = i

x = ± 6i