Answer:
D
Step-by-step explanation:
To obtain vertex form from the given equation use the method of completing the square
given 8y + x² = - y² - 181 + 26x
rearrange having the x terms and y terms together
add y² to both sides
8y + x² + y² = - 181 + 26x ( subtract 26x from both sides )
x² - 26x + y² + 8y = - 181
add (half the coefficient of the x/y terms )² to both sides
x² + 2(- 13)x + 169 +y² + 2(4)y + 16 = - 181 + 169 + 16
completing the square on both the x and y terms
(x - 13)² + (y + 4)² = 4 → D
Answer: the third one
Step-by-step explanation:
9r
Explanation:
4r + 9r = 13r
13r-11r = 2r
2r + 7r = 9r
Answer:
43
Step-by-step explanation:
Let
The unit digit = x
The tens digit = y
The number = 10x + y
The tens digit of a two-digit number is five more than the units digit.
y = x + 5
Seven times the sum of the digits of this number is 3 less than the number itself.
7(x + y) = 10x + y - 3
7x + 7y = 10x + y - 3
Find the number.
We substitute x + 5 for y
7x + 7(x + 5) = 10x + (x + 5) - 3
7x + 7x + 35 = 10x + x + 5x - 3
14x + 35 = 11x + 5x - 3
Collect like terms
35 + 3 = 11x + 5x -14x
38 = 16x - 14x
38 = 2x
x = 38/2
x = 19
Solving for y
y = x + 5
y = 19 + 5
y = 24
The number = 19 + 24
= 43
