C. I used the app math way. it has been a lifesaver.
The cost of each Piano Lesson = $30
If there are x lessons, the total cost of lessons can be expressed as 30x.
Since the number of lessons cannot be negative, the value of x can be 0 or greater than 0, where x=0 shows no lesson.
For 1 lesson, x = 1
So the cost will be = 30(1) = $30
In ordered pair we can write it as (1, 30)
If we consider there is an option to attend half portion of a lecture, then for 1 and half lectures, x = 1.5
So, the cost for 1.5 lectures will be = 30(1.5) = $45
In ordered pair we can write it as (1.5, 45)
For 3 lesson, x = 3
The cost of 3 lessons will be = $90
In ordered pair we can write this as (3, 90)
So, from the given options, only following 2 ordered pairs satisfy the given conditions:
1) (1,30)
2) (3, 90)
The tangent to through (1, 1, 1) must be perpendicular to the normal vectors to the surfaces and at that point.
Let . Then is the level curve . Recall that the gradient vector is perpendicular to level curves; we have
so that the gradient of at (1, 1, 1) is
For the surface , we have
so that . We can obtain a vector normal to by taking the cross product of the partial derivatives of , and evaluating that product for :
Now take the cross product of the two normal vectors to and :
The direction of vector (24, 8, -8) is the direction of the tangent line to at (1, 1, 1). We can capture all points on the line containing this vector by scaling it by . Then adding (1, 1, 1) shifts this line to the point of tangency on . So the tangent line has equation
What is the bottom equation?