A is the point with coordinate (2,10) B is the point with coordinate (5,d)
The gradient of the line AB is 4
Work out the value of d

d = 22

Step-by-step explanation:

Substitute given slope and A to the equation y = mx + b to find b

y= mx + b

10 = 4.2 +b

10 = 8 + b

10 - 8 = 8 - 8 + b

b = 2

Then we have y = 4x + 2 when we substitute b and m.

They give x value of point B, we can plug it in and find y value which is d in this question.

y = 4x + 2

y = 4.5 +2

y = 22

Therefore, d = 22

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12