7x7+3(5.2-2.8) evaluate the express

56.2

Step-by-step explanation:

Use your order of operations to solve this and you will understand how to do more like these in the future. Especially when your solving multi step equations. PEMDAS look it up and learn it by heart, it will help you so  much in the future

56.2

Step-by-step explanation:

7x7+3(5.2-2.8)  

Use GEMDAS:

Grouping Symbols | [ ] ( )

Exponents | ^2

Multiplication | 7x7

Division | 9/18

Addition | 1+1

Subtraction | 2-1

Go in order using this method. If nothing is left but one thing, go from left to right. Sometimes, not everything will be there.

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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