Answer:
Step-by-step explanation:
12a)To rationalize the denominator, multiply the denominator and numerator by √5.

b) (a+b)² = a² + 2ab + b²
(1 +√3)² = 1² + 2*1*√3 + (√3)²
= 1 + 2√3 + 3
= 4 + 2√3
a = 4 ; b =2
13) (a + b)(a - b) = a² - b²

Answer:
????
Step-by-step explanation:
number 1 could be 2 different answers
Answer:
B, C, E
Step-by-step explanation:
Elena’s aunt pays her $1 for each call she makes to let people know about her aunt’s new business. The table shows how much money Diego receives for washing windows for his neighbors.
Select all the statements about the situation that are true.
A. Elena makes more money for making 10 calls than Diego makes for washing 10 windows.
Elena:
$1 = 1 call
$10 = 10 calls
Diego:
27 windows = $30
10 windows = $x
Cross product
27*x = 30*10
27x = 300
x = 300/27
x = $11.11
Statement A not true
B. Diego makes more money for washing each window than Elena makes for making each call.
Diego:
10 windows = $11.11
Each window = $11.11/10
= $1.11
Statement B is true
C. Elena makes the same amount of money for 20 calls as Diego makes for 18 windows
Elena:
20 calls = $20
Diego:
18 windows = 18 × $1.11
= $19.98
Approximately $20 to the nearest whole dollar
Statement C is true
D. Diego needs to wash 35 windows to make as much money as Elena makes for 40 calls.
Diego
35 × $1.11 = $38.85
Approximately $39
Elena:
40 calls = $40
Statement D is not true
E. The equation y = x, where y is the number of dollars and x is the number of calls, represents Elena’s situation.
Statement E is true
Answer:

Step-by-step explanation:
The formula of an area of a rectangle:

l - length
w - width
We have

Substitute:
<em>divide both sides by 15</em>

The formula of a perimeter of a rectangle:

Substitute:
