If x + √(x² – 9) = 9 then find the value of x – √(x² – 9).
WBBSE
Class X
Mathematics
Quadratic Surds
02 Mark
2023
x + √(x² – 9) = 9
or, 9 – x = √(x² – 9)
squaring both sides
(9 – x)² = {√(x² – 9)}²
or, 81 – 18x + x² = x² – 9
or, 81 – 18x = – 9
or, 18x = 90
or, x = 5
Now, x – √(x² – 9) = 5 – √(5² – 9)
= 5 – √16
= 5 – 4 = 1
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