Arnold K H Tan's answer to .....'s Secondary 3 A Maths Singapore question.
done
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clear
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Factorise, before solving.
Date Posted:
2 years ago
sorry, but i think the answer is not complete ...
have to consider ...
[r^4 term in (1-3r)^12] x [r^0 term in (1-r)^12]
+[r^3 term in (1-3r)^12] x [r^1 term in (1-r)^12]
+[r^2 term in (1-3r)^12] x [r^2 term in (1-r)^12]
+[r^1 term in (1-3r)^12] x [r^3 term in (1-r)^12]
+[r^0 term in (1-3r)^12] x [r^4 term in (1-r)^12].
have to consider ...
[r^4 term in (1-3r)^12] x [r^0 term in (1-r)^12]
+[r^3 term in (1-3r)^12] x [r^1 term in (1-r)^12]
+[r^2 term in (1-3r)^12] x [r^2 term in (1-r)^12]
+[r^1 term in (1-3r)^12] x [r^3 term in (1-r)^12]
+[r^0 term in (1-3r)^12] x [r^4 term in (1-r)^12].
You are right! Thanks. Pretty tedious question... so likely easier to let a = 1 and b = 3r² - 4. Even then, the student must be careful to avoid missing out terms that yield r⁴
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