Lucia tried to solve the system below. lucia’s work. what error did lucia make? when lucia solved for the value of x, she subtracted 2y from both sides. when lucia solved for the value of y, she treated –2y as 2y. when lucia solved for the value of x, she added 18 to both sides. when lucia solved for the value of x, she treated –2(–9) as 18 instead of –18.

A. When Lucia solved the second equation for x, she subtracted 2y from both sides. EDG 2021

Step-by-step explanation:

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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

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step-by-step explanation: