Answer:
Step 4 is incorrect he did not divide correctly from step3 to step 4
Step-by-step explanation:
The circumference of a circle is
C = 2 * pi *r
We know the circumference is 12 pi
12pi = 2 pi *r
Divide each side by 2 pi
12 pi/2pi = 2pi r/ 2pi
6 = r
From step 3 The student did not cancel the pi in the top and the bottom on the right hand side to isolate r
In step 4 he got 6 =pi r instead of pi
Let 11x + 15y + 23 = 0 be equation (1)
And 7x - 2y - 20 = 0 be equation (2)
Multiply equation (1) by 2:
22x + 30y + 46 = 0
Multiply equation (2) by 15:
105x - 30y - 300 = 0
Add equations (1) and (2):
22x + 105x + 30y - 30y + 46 - 300 = 0
127x - 254 = 0
127x = 254
x = 254/127
[x = 2]
Substitute x = 2 in equation (1) to find y:
11(2) + 15y + 23 = 0
22 + 15y + 23 = 0
15y + 45 = 0
15y = -45
y = -45/15
y = -3
Therefore, x = 2 and y = -3.
Answer:

Step-by-step explanation:
The equation of the curve is

To find the equation of tangent we need to differentiate this equation w.r.t x
So, differentiating we get

This would give the slope of the tangent line at any given point of which x coordinate is known. In the present case it is 
Then slope would accordingly be

= ∞
For,
, 
Equation of tangent line, in the point slope form, would be 
y=-x-5. you just need to add 1 to another side to get rid of 1 from the left side
Answer:
17576
Step-by-step explanation:
As L can be anything from A to Z , there are 26 combinations for that and as repetition is allowed, for second and third letters, we again have 26 combinations available and thus 26×26×26=17576 combinations for letters.