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secondary 3 | A Maths
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Date Posted: 4 years ago
Views: 645
(i)
do a complete-the-sq
2x² - x + 1
= 2(x - ¼)² + ⅞
since
1. 2(x - ¼)² is always +ve &
2. ⅞ is +ve
then
2x² - x + 1 is always +ve
(ii)
(3x² - 19x + 20)/(2x² - x + 1) > 0
since 2x² - x + 1 is always +ve ;
=> 3x² - 19x + 20 > 0
=> (3x - 4)(x - 5) > 0
=> x < 4/3 or x > 5
.
.
.
do a complete-the-sq
2x² - x + 1
= 2(x - ¼)² + ⅞
since
1. 2(x - ¼)² is always +ve &
2. ⅞ is +ve
then
2x² - x + 1 is always +ve
(ii)
(3x² - 19x + 20)/(2x² - x + 1) > 0
since 2x² - x + 1 is always +ve ;
=> 3x² - 19x + 20 > 0
=> (3x - 4)(x - 5) > 0
=> x < 4/3 or x > 5
.
.
.
See 1 Answer
done
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Two different approaches for part i
Date Posted:
4 years ago
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