4y = 8.4 what is the value of y?
also pls include an explanation for this along with a check ( a sentence to check the answer ) and property ( commutative, associative, distributive, or identity ) ;-; ill give 5 stars and a thanks

2.1

Step-by-step explanation:

You divide 8.4 by 4 hope this helps

Work Shown:

4y = 8.4

4y/4 = 8.4/4   divide both sides by 4; division property of equality

y = 2.1

Check:

4y = 8.4

4*2.1 = 8.4 replace y with 2.1

8.4 = 8.4

We end up with a true equation, as we get the same number on both sides, so we've confirmed the answer.

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

sites: