Question

Find a ⋅ b.

a = 4i - 4j, b = 4i + 5j

help me please

Answer 1

Answer on Question#42438 – Math - Analytic Geometry

Find $a \cdot b$.

$$a = 4i - 4j, \quad b = 4i + 5j$$ $$a = a_1i + a_2j$$ $$b = b_1i + b_2j$$

Use formula for find scalar product

$$a^{\rightarrow} \cdot b^{\rightarrow} = a_1b_1 + a_2b_2$$ $$a^{\rightarrow} \cdot b^{\rightarrow} = 4 \cdot 4 + (-4 \cdot 5) = -4$$

Answer: -4.

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