Answer:
Step-by-step explanation:
90x - 60y = 68.....multiply by -1
90x - 70y = 91
---------------------------
-90x + 60y = -68 (result of multiplying by -1)
90x - 70y = 91
---------------------------add
-10y = 23
y = -23/10 <===
90x - 60y = 68
90x - 60(-23/10) = 68
90x + 138 = 68
90x = 68 - 138
90x = - 70
x = -70/90
x = -7/9 <=====
Answer:
y = 2x + 0 or y = 2x
Step-by-step explanation:
use slope-intercept form
12 - 10 = 2
6 - 5 = 1
m value = 2/1 = 2
y=2x+b
to find b plug one of the points in for x and y
Example: 10 = 2(5) + b
solve equation
10 = 10 + b
subtract 10 from both sides
0 = b
Equation of line equals y=2x+0 or simply just y=2x
X² + 8x +y² - 2y -64 =0
We see that the equation has x² and y² . Also we see that coefficients in front of x² and y² are equal. So this is an equation of the circle.
(x² + 8x) +(y² - 2y) -64 =0
(x² + 8x) +(y² - 2y) = 64
We need to complete square for x and y groups, that means it should be written in form (a+b)² or (a-b)².
Expressions in parenthesis we will write as a²+/-2ab+b², to write it after as (a+/-b)², because a²+/-2ab+b² = (a+/-b)²
(x² + 2*4x) +(y² - 2*1y) = 64
(x² + 2*4x+4²) +(y² - 2*1y+1²) = 64+4²+1²
(x+4)² + (y-1)²= 81 Sometimes this is called a standard form of the circle.
(x+4)² + (y-1)²= 9² Sometimes it is required to write like this.
And if you are studying circles,ellipses and hyperbolas, the standard form should look like
The residue in each case is the difference between actual and predicted sales. Thus:
55 - 40 = 15
150 - 150 = 0
325 - 300 = 25
510 - 500 = 10
800 - 780 = 20
1000 - 990 = 10
These add up to be:
15 + 25+ 10 +20 +10
= 80