4 = 2 * 2
Multiplying by 2 is the same a doubling.
Since 4 is 2 * 2, to multiply a number by 4, double the number twice.
Example:
What is 4 * 100?
Double 100 to get 200.
Double 200 to get 400.
Therefore, 4 * 100 = 400.
By doubling twice, we do the same as multiplying by 4.
Answer:
Step-by-step explanation:
x-y=7
-3x+9y=-39
Divide the second equation by 3
-x +3y = -13
Add this to the first equation
x-y=7
-x +3y = -13
----------------------
0x +2y = -6
Divide by 2
2y/2 = -6/2
y = -3
Now find x
x-y = 7
x -(-3) = 7
x+3 = 7
Subtract 3 from each side
x = 4
(4,-3)
Or by substitution
x-y=7
solve for x
x = 7+y
-3x+9y=-39
Substitute y+7 in for x
-3(7+y) +9y = -39
Distribute
-21 -3y +9y = -39
Combine like terms
-21 +6y = -39
Add 21 to each side
6y = -18
you would do PEMDAS
you do -3 times 4. then you do that and devide by -3.
Answer:
y = 7.8x + 26
Step-by-step explanation:
Given the following :
Pearson's r = 0.78
Average consumption of ice cream = 5 grams per week (m) with Standard deviation (sd) = 1.5 grams
Average weight = 65 kg with standard deviation of 15kg
Formular for the regression line :
General regression formula :
y = mx + c
y = predicted variable ; m = slope or gradient ; x = predictor variable ; c = intercept
Gradient (m) = change in y / change in x
m = (sd y / sd x) * r
m = (sd weight / sd ice cream) × r
m = (15 / 1.5) × r
m = 10 × 0.78 = 7.8
Intercept:
mean of weight(y) - [Slope×mean of icecream(x)]
65 - [7.8 × 5]
65 - 39 = 26
Hence,
y = 7.8x + 26
Answer:
a. x = -9 or x = -2
b. -5(x - 4)
c. x = -3 or x = 5
d. x = ±7
Step-by-step explanation:
a. First person;
y = x² + 11x + 18
y = x² + 9x + 2x + 18
y = x(x + 9) + 2(x + 9)
y = (x + 9)(x + 2)
y = x = -9 or x = -2
b. Second person;
y = -5x + 20
The common factor is 5.
y = -5(x - 4)
c. Third person;
y = x² - 2x - 15
y = x² - 5x + 3x - 15
y = x(x - 5) + 3(x - 5)
y = (x + 3)(x - 5)
y = x = -3 or x = 5
d. Fourth person;
y = x² - 49
Applying the difference of squares formula;
(a² - b²) = (a - b)(a + b)
y = x² - 49 = x² - 7² = (x - 7)(x + 7)
y = (x - 7)(x + 7)
y = x = ±7
