Which of the following expressions is equal to x2 +25? O A. (x+10)(x-15)
O B. (x-51)(x+51)
OC.
-512
O D. (x+5)

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Solution given:

x²+25=???

we have

formula

a²+b²=(a+b)²-2ab or (a-b)²+2ab

so

x²+25 =x²+5²=(x+5)²-2x*5=(x+5)²-10x

or

x²+25=x²+5²=(x-5)²+2x*5=(x-5)²+10x

:.

expressions is equal to x² +25 is

(x-5)²+10x

or

(x+5)²-10x

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