a constant of proportionality is a number you have to multiply x by to get y.
y=kx is the equation that expresses the proportionality of x and y
the constant of proportionality is k, so k=-5
Answer:
C
Step-by-step explanation:
The equation of a parabola in vertex form is
y = a(x - h)² + k
where (h, k) are the coordinates of the vertex and a is a multiplier
Given
y = 2x² + 12x + 1
To express in vertex form use the method of completing the square.
The coefficient of the x² term must be 1 , thus factor out 2 from 2x² + 12x
y = 2(x² + 6x) + 1
add/ subtract ( half the coefficient of the x- term)² to x² + 6x
y = 2(x² + 2(3)x + 9 - 9) + 1
= 2(x + 3)² - 18 + 1
= 2(x + 3)² - 17 → C
Half Tens is a way of multiplying where we have to find the value of given numbers. First we double any 'one' of the two given numbers and multiply both to get an answer. Then we divide that answer by '2' to get the answer.
Lets take two numbers as 16 and 340

Double the number 16

Now we will divide this by 2

So, if we check
, it is 5440.
Similarly if we double the number 340, we get 680
Now, 
And 10880/2 = 5440
Hence, in both ways the answer is 5440.