Tyna simplified the expression StartFraction 3 x cubed Over 12 x Superscript negative 2 Baseline EndFraction to StartFraction x Over 4 EndFraction. What was Tyna's mistake? She divided the coefficients incorrectly. She added the exponents instead of subtracting them. She divided the coefficients instead of subtracting them. She subtracted the exponents instead of dividing them.

She divided the coefficients incorrectly

Step-by-step explanation:

A. She divided the coefficients incorrectly.

B. She added the exponents instead of subtracting them.

C. She divided the coefficients instead of subtracting them.

D. She subtracted the exponents instead of dividing them.

Correct calculation:

3x³/12x^-2

= 3x³ ÷ 12x^-2

= 3x³ ÷ 1/12x²

= 3x³ × 12x²/1

= 36x^5

Tyna's calculation:

3x³/12x^-2 = x/4

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