WAEC offline past questions - with all answers and explanations in one app - Download for free
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts

Given that \(P = \begin{pmatrix} 1 & 3 \\ 2 & -5 \end{pmatrix}\) and Q =...

Mathematics
JAMB 2025

Given that \(P = \begin{pmatrix} 1 & 3 \\ 2 & -5 \end{pmatrix}\) and Q = \(\begin{pmatrix} 3 & -7 \\ 1 & 2 \end{pmatrix}\) . Find P + 2Q

  • A. \(\begin{pmatrix} 7 & -11 \\ 4 & -1 \end{pmatrix}\)
  • B. \(\begin{pmatrix} 7 & -11 \\ 4 & -9 \end{pmatrix}\)
  • C. \(\begin{pmatrix} -7 & 11 \\ -4 & -1 \end{pmatrix}\)
  • D. \(\begin{pmatrix}11 & -7 \\ 4 & -1 \end{pmatrix}\)
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Post UTME Past Questions Agent
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Correct Answer: Option A
Explanation

Given  \(P = \begin{pmatrix} 1 & 3 \\ 2 & -5 \end{pmatrix}, \quad Q = \begin{pmatrix} 3 & -7 \\ 1 & 2 \end{pmatrix}\)

we need to find \(P + 2Q\).

First, calculate \(2Q\): \(2Q = 2 \begin{pmatrix} 3 & -7 \\ 1 & 2 \end{pmatrix} = \begin{pmatrix} 2 \cdot 3 & 2 \cdot -7 \\ 2 \cdot 1 & 2 \cdot 2 \end{pmatrix} = \begin{pmatrix} 6 & -14 \\ 2 & 4 \end{pmatrix}\)

Now add \(P\) and \(2Q\):

\(P + 2Q = \begin{pmatrix} 1 & 3 \\ 2 & -5 \end{pmatrix} + \begin{pmatrix} 6 & -14 \\ 2 & 4 \end{pmatrix} = \begin{pmatrix} 1 + 6 & 3 + (-14) \\ 2 + 2 & -5 + 4 \end{pmatrix}\)

Calculating each entry, we find:

\(= \begin{pmatrix} 7 & -11 \\ 4 & -1 \end{pmatrix}\)

Thus, the result of \(P + 2Q\) is  \(\begin{pmatrix} 7 & -11 \\ 4 & -1 \end{pmatrix}\)

There is an explanation video available below.


Report an Error Ask A Question Download App
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 127076
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now

Explanation Video

WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
WAEC offline past questions - with all answers and explanations in one app - Download for free
Post UTME Past Questions Agent

Contributions ({{ comment_count }})

Please wait...

{{ settings.no_comment_msg ? settings.no_comment_msg : 'There are no comments' }}

Quick Questions

Post your Contribution

Please don't post or ask to join a "Group" or "Whatsapp Group" as a comment. It will be deleted. To join or start a group, please click here

{{ quote.posted_by.display_name }}
{{ settings.form_textarea_description }}
 
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Post UTME Past Questions Agent
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 127076
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
WAEC offline past questions - with all answers and explanations in one app - Download for free
Post UTME Past Questions Agent
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 127076
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now