I have to rewrite the expressions because they look very confusing.
1) The given fractions to add are:
4p² + 6 2p - 2
------------ + ------------
4p² 10p²
2) The statements to asses are:
A) The least common denominator is 20p
.
B) The first fraction rewritten with the LCD is (20p² +30) / 20p²
C) The second fraction rewritten with the LCD is (4p - 4) / 20p
D) The sum is (24p² -4p +30 ) / 20p² = (12p-2p+15) / 10p^2
E) The sum is a rational expression.
This is the result for each statement.
A) The least common denominator is 20p
FALSE: THE LCD IS 20p², because it the least expression that contains all the prime factors of both denominators: 4p² and 10p.
See that you cannot divide 20p by 4p² but you can divide 20p² by 4p² and 10 p. So, 20p is not a common denominator.
.
B) The first fraction rewritten with the LCD is (20p² +30) / 20p²
TRUE: you get this expression from the first fraction by multiplying both numerator and denominator by 20p² / 4p² = 5:
(4p² + 6)×5 = 20p² + 30
(4p²)×5 = 20p²
=>
20p² + 30
--------------
20p²
C) The second fraction rewritten with the LCD is (4p - 4) / 20p
FALSE: you have to multiply both numerator an denominator by 20p² / 10p = 2p
(2p - 2) × 2p = 4p² - 4p
10p × 2p = 20p²
So, the second fraction rewritten with the LCD is:
4p² - 4p
-----------
20p²
D) The sum is (24p² - 4p +30 ) / 20p² = (12p-2p+15) / 10p²
TRUE
20p² + 30 4p² - 4p 24p² - 4p + 30
-------------- + --------------- = ----------------------
20p² 20p² 20p²
And when you simplify the last fraction dividing by 2 you get:
12p² - 2p + 15
-----------------------
10p²
E) The sum is a rational expression.
TRUE:
The sum of rational number has the closure property which means that by adding rational expression you will always ge a rational expression.
