Please help.
Is algebra.

Answers:

So the solution is (x,y) = (4, -1)

Work Shown:

6x + 7y = 17

6x + 7( y ) = 17

6x + 7( -3x+11 ) = 17 ... replace every copy of y with -3x+11

6x - 21x + 77 = 17

-15x = 17-77

-15x = -60

x = -60/(-15)

x = 4

We'll use this x value to find y

y = -3x+11

y = -3(4)+11 ... replace x with 4

y = -12+11

y = -1

We have  x = 4 and y = -1 pair up together to give us the solution (x,y) = (4, -1)

To check the solution, we plug x = 4 and y = -1 into each equation

Plugging the values into the first equation leads to...

y = -3x+11

-1 = -3(4)+11

-1 = -1

This is effectively already done in the last part of the previous section. But it doesn't hurt to verify like this regardless.

We'll need to verify the second equation as well.

6x + 7y = 17

6(4) + 7(-1) = 17

24 - 7 = 17

17 = 17

We get a true equation, so the solution is confirmed with both equations. Overall, the solution to the system of equations is confirmed. This system is independent and consistent.

19.

step-by-step explanation:

you add the 9 in the tens column since it is a single digit and 9 plus zero is 9 so it is 19

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