-2x - 5y = -1 8x + 4y = 16

To start solving the system of equations above, what number would be a good option to multiply the top equation by?

If someone could answer this asap that would really help also doing brainliest answer!

The good option to multiply the top equation by is -4

This is because, when we solve the equations, in the left side of first equation :-

☆ -2 can be multiplied by -4 to get the value 8 on the left side of second equation.

☆ This can help in easier elimination in the given set of equations.

■ The process is to be done as per the given below way :

Now the 8x on both equations can be cut.

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

answer: there are 453.592 grams in a pound.