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Question

Question 3
Which of the following equations has 2 as a root?
(a)
x24x+5=0
(b) x2+3x12=0
(c) 2x27x+6=0
(d) 3x26x2=0​​​​​​​

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Solution

a) Substituting x = 2 in x2 - 4x + 5, we get (2)2 – 4(2) + 5
= 4 – 8 + 5 = 1 0
So, x = 2 is not a root of x2 – 4x + 5 = 0
b)
Substituting x = 2 in x2+3x12, we get
(2)2 + 3(2) – 12
= 4 + 6 – 12 = - 2 0
So, x = 2 is not a root of x2 + 3x – 12 = 0
c)
Substituting x= 2 in 2x2 – 7x + 6, we get
= 2(2)2 – 7(2) +6)
= 8 – 14 +6 = 0
So, x = 2 is a root of 2x27x+6=0
d ) Substituting x = 2 in 3x26x2 ​​​​​, we get
= 3(2)2 – 6(2) – 2
= 12 – 12 – 2 = - 2 0
So, x = 2 is not a root of 3x26x2=0​​​​​​​​​​​​​​


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