Question

Find a ⋅ b.

Answer 1

a.b = 9.5 + (-6).5=15

Answer 2

Answer:

The correct option is d. 15

Step-by-step explanation:

Consider the provided information.

We need to find the  a ⋅ b

The given vector is:

a = 9i - 6j, b = 5i + 5j

$\vec{a} = 9i - 6j \cdot \vec{b}= 5i + 5j$

Use the vector multiplication as shown:

$a = a_1, a_2,…, a_n\ \text{and}\ b = b_1, b_2,…, b_n$ is defined as:

$a\cdot b =a_1b_1+a_2b_2...a_nb_n$

Now by using the above formula:

$\vec{a}=9i-6j\cdot \vec{b}= 5i + 5j=45-30=15$

Hence, the correct option is d. 15