begin pmatrix -2 amp 1 2 amp 3 end pmatrix begi... - JAMB Mathematics 2008 Question
\(\begin{pmatrix} -2 & 1 \ 2 & 3 \end{pmatrix}\) + \(\begin{pmatrix}p & q \ r & s\end{pmatrix}\) = \(\begin{pmatrix} 1 & 0 \0 & 1 \end{pmatrix}\). What is the value of r?
A
-\(\frac{1}{8}\)
B
\(\frac{3}{8}\)
C
\(\frac{5}{8}\)
D
\(\frac{1}{4}\)
correct option: d
-2p + r = 1.......(i)
2p + 3r = 0.......(ii)
r - 1 + 2p ........(iii)
2p + 3(1 + 2p) = 0
2p + 3(1 + 2p) = 0
2p + 3 + 6p = 0
3 - 8p = 0 \(\to\) 8p = 3
p = \(\frac{3}{8}\)
6 = 1 - 2 \(\frac{3}{8}\)
= 1 - \(\frac{6}{8}\)
\(\frac{8 - 6}{8}\) = \(\frac{2}{8}\)
= \(\frac{1}{4}\)
2p + 3r = 0.......(ii)
r - 1 + 2p ........(iii)
2p + 3(1 + 2p) = 0
2p + 3(1 + 2p) = 0
2p + 3 + 6p = 0
3 - 8p = 0 \(\to\) 8p = 3
p = \(\frac{3}{8}\)
6 = 1 - 2 \(\frac{3}{8}\)
= 1 - \(\frac{6}{8}\)
\(\frac{8 - 6}{8}\) = \(\frac{2}{8}\)
= \(\frac{1}{4}\)
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