Question

the sum of -15/32 and 7/31 is which of the following answers: 1/4, -11/16, -1/8, -1/4

Answer 1

Answer:

-11/16

Step-by-step explanation:

Answer 2

1) Find the Least Common Denominator (LCD) of $\frac{15}{32} ,\frac{7}{31}$ In other words, find the Least Common Multiple (LCM) of 32,31.

Method 1: By Listing Multiples

1. List the multiples of each number.

Multiples of 32: 31,64,96,... 928, 960 ,992,...

Multiples of 31: 31, 62, 93 , ... , 930, 961 , 992, ...

Find the smallest number that is shared by all rows above. This is the LCM.

LCM = 992

Method 2: By Prime Factors

1. List the prime factors of each number.

Prime Factors of 32: 2,2,2,2,2

Prime Factors of 31: 31

2.  Find the union of these primes.

2,2,2,2,2,31

3. Multiply these numbers: 2 * 2 * 2 * 2 * 2 * 31 = 992. This is the LCM.

LCM = 992

2) Make the denominators the same as the LCD.

$-\frac{15*31}{32*31} +\frac{7*32}{31*32}$

3) Simplify. Denominators are now the same.

$-\frac{465}{992} +\frac{224}{992}$

4) Join the denominators.

$\frac{-465+224}{992}$

5) Simplify

$-\frac{241}{992}$

Decimal Form: -0.242944