Given that a = 3i + 4j and b = i - 2j, find |a + b|.
A√20CORRECT
B√40
C√52
D√68
GCEFurther MathematicsVectors2023
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Why the answer is A, and why the others tempt you.
a + b = (3+1)i + (4-2)j = 4i + 2j. The magnitude is √(4² + 2²) = √(16 + 4) = √20.
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