JAMB - Mathematics (1978 - No. 42)
The vectors a and b are given in terms of two perpendicular units vectors i and j on a plane by a = 2i - 3j, b = -i + 2j. Find the magnitude of the vector a + 3b
2
4
\(\sqrt{10}\)
35
2.2
คำอธิบาย
a = 2i - 3j - 3i + 6j
= -i + 3j
= \(\sqrt{5 \times 2}\)
= \(\sqrt{10}\)
= -i + 3j
= \(\sqrt{5 \times 2}\)
= \(\sqrt{10}\)