[SIMPLE]Please solve:
(for values of k for which the given equation has real and equal roots):
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D= b² - 4ac =0
[2(k-12)]² - 4×( k-12)×(2) =0
4 ( k² - 24k + 144 ) - 8k + 96 =0
4k² - 96k + 576 - 8k + 96 = 0
4k² - 104 k +672 = 0
k² -2 6k +168 =0
By factorising method
k² - 14k - 12k +168 = 0
k×( k-14) -12× (k-14) =0
(k-12)(k-14)=0
k=12 or k=14
But k = 12 cannot satisfy the equation . So the value for k is 14.
K = 14.
[2(k-12)]² - 4×( k-12)×(2) =0
4 ( k² - 24k + 144 ) - 8k + 96 =0
4k² - 96k + 576 - 8k + 96 = 0
4k² - 104 k +672 = 0
k² -2 6k +168 =0
By factorising method
k² - 14k - 12k +168 = 0
k×( k-14) -12× (k-14) =0
(k-12)(k-14)=0
k=12 or k=14
But k = 12 cannot satisfy the equation . So the value for k is 14.
K = 14.
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but for k=12, the equation doesn't hold anymore.(it becomes 2=0). so we need to exclude 12. just remove the 12.