Which property of multiplication is shown below? If x = 3 + 4i and y = 5 + 6i, x × y = y × x.

Verified Answer :

This is the commutative property.

Answer:

Commutative property of multiplication

Step-by-step explanation:

According to commutative property of multiplication , for two elements x and y , we have \(x\times y=y\times x\) .

Here, \(x = 3+4 i , y= 5+6 i\)

We will also use property : \((a+b)(c+d)=a(c+d)+b(c+d)\)

\(x\times y=\left ( 3+4i \right )\left ( 5+6i \right )\\=3\left ( 5+6i \right )+4i\left ( 5+6i \right )\)

Also, we know that \(i^2 = -1\)

Therefore,

So,

\(x\times y=\left ( 3+4i \right )\left ( 5+6i \right )\\=3\left ( 5+6i \right )+4i\left ( 5+6i \right )\\=15+18i+20i+24i^2\\=15+18i+20i-24\\\)

On adding real and imaginary parts separately , we get

\(x\times y=15+18i+20i-24\\=\left ( 15-24 \right )+i\left ( 18+20 \right )\\=-9+38i\)

\(y\times x=\left ( 5+6i \right )\left ( 3+4i \right )\\=5\left ( 3+4i \right )+6i\left ( 3+4i \right )\\=15+20i+18i+24i^2\\=\left ( 15-24 \right )+i\left ( 20+18 \right )\\=-9+38i\)

So, \(x\times y=y\times x\) .

Hence, commutative property is verified .