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- If a and b are the roots of the equation x2 - 9x + 20 = 0, find the value of a2 + b2 + ab?
Question 1:
If a and b are the roots of the equation x2 - 9x + 20 = 0, find the value of a2 + b2 + ab? A. -21
B. 1
C. 61
Feedback a2 + b2 + ab = a2 + b2 + 2ab - ab
i.e., (a + b)2 - ab
from x2 - 9x + 20 = 0, we have
a + b = 9 and ab = 20. Hence the value of required expression 81 - 20 = 61.
i.e., (a + b)2 - ab
from x2 - 9x + 20 = 0, we have
a + b = 9 and ab = 20. Hence the value of required expression 81 - 20 = 61.
D. 21
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