Answer:
7 hours 30min
Step-by-step explanation:
Step one :
Given data
We are told that Erica can paint 1 room in 5hours
Her work rate is 1/5 room per hour
And also with the assistance of her friend they can paint 1 room in 3 hours
Hence their combined work rate is 1/3 room per hour
Step two
The combined work expression is
1/A+1/B=1/T
Where A=Erica's work rate
B=Rachael's work rate
T=combined work
1/5+1/B=1/3
1/B=1/3-1/5
1/B=5-3/15
1/B=2/15
B=15/2
B=7.5 hours
It will take Rachel 7 hours 30min to paint the room
The value of the expression 4(5² - 3 - 2x)² is <u>576</u>.
In the question, we are asked to evaluate the expression 4(5² - 3 - 2x)², where x = 5.
To find the value of the expression, we find the value of each term with the value assigned to the variable and then put back the terms in the expression to get the final value.
The term 5² = 25.
The term 2x, when x = 5, can be shown as 2x = 2*5 = 10.
Taking the terms back to the expression, we get:
4(5² - 3 - 2x)²
= 4(25 - 3 - 10)²
= 4(12)²
= 4(144)
= 576.
Thus, the value of the expression 4(5² - 3 - 2x)² is <u>576</u>.
Learn more about solving expressions at
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Answer:
A. real numbers, rational numbers
Step-by-step explanation:
An integer is a whole number, -2/15 is not whole. It is real and rational.
The equation is equivalent to 1/cos(2x)-2=sin(2x)/cos(2x). Make the denominator cos(2x) for all terms, we get 1-2cos(2x)=sin(2x). Since cos^2(2x)+sin^2(2x)=1, let cos(2x)=a, substitute sin(2x) by +-\sqrt(1-a^2), and solve the equation with only one variable a. We get a=4/5 or 0, but cos(2x) cannot be 0, otherwise sec(2x) is undefined. 2x=36.9 degrees, so x=18.9 degrees approximately.
