12. The sum of two irrational numbers multiplied by the larger one is 70 and their difference
is multiplied by the smaller one is 12; the two numbers are
a) 372, 273
b) 572,315 c) 272,572 d) none of these.
Answers
Answer:
d) none of these.
Step-by-step explanation:
Let the two irrational numbers be √a and √b, where a and b are positive integers but not a perfect square with √a > √b
By the given conditions,
√a (√a + √b) = 70
or, a + √(ab) = 70 ..... (1)
√b (√a - √b) = 12
or, √(ab) - b = 12 .... (2)
Now {(1) - (2)} gives
a + b = 58
or, a = 58 - b
Putting a = 58 - b in (1), we get
58 - b + √{b (58 - b)} = 70
or, 58 - b + √(58b - b²) = 70
or, √(58b - b²) = b + 12
or, 58b - b² = b² + 24b + 144
or, 2b² - 34b + 144 = 0
or, b² - 17b + 72 = 0
or, b² - 9b - 8b + 72 = 0
or, b (b - 9) - 8 (b - 9) = 0
or, (b - 9) (b - 8) = 0
Either b - 9 = 0 or, b - 8 = 0
This gives b = 9, 8
Since b is not a perfect square, we take b = 8
Then a = 58 - 8 = 50
So √a = √50 = 5√2
and √b = √8 = 2√2
Therefore the two irrational numbers are 5√2 and 2√2