Question

Find a • b. a = 5i + 7j, b = -4i + 3j (5 points)

<1, 10>
<-20, 21>
1
41

Answer 1

1

Explanation:

Answer 2

`a\cdot b` = 1

Explanation:

Given that,

Vector
`a=5i+7j`

Vector
`b=-4i+3j`

We need to find
`a{\cdot} b` means the dot product of a and b. So,

`a{\cdot} b=(5i+7j){\cdot} (-4i+3j)`

We know that,

`i{\cdot}i, j{\cdot}j,k{\cdot}k=1\ \text{and}\ i{\cdot}j= j\cdot i=0`

So,

`a{\cdot} b=(5i+7j){\cdot} (-4i+3j)\\\\=5i{\cdot}(-4i)+5i{\cdot} 3j+7j\cdot(-4i)+7j\cdot 3j\\\\=-20+21\\\\=1`

So, the value of
`a\cdot b` is 1.