Multiple choice

State the following statement is True or False If both the roots of the equation $x^2-6ax+2-2a+9a^2=0$ exceed $3$, then $a<\dfrac {11}9$

  1. True

  2. False

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Roots > 3. Let f(x) = x^2 - 6ax + 9a^2 - 2a + 2 = 0. (x-3a)^2 = 2a - 2. x = 3a +/- sqrt(2a-2). Roots are 3a + sqrt(2a-2) and 3a - sqrt(2a-2). Both > 3: 3a - sqrt(2a-2) > 3 => 3a - 3 > sqrt(2a-2). Square both sides: 9(a-1)^2 > 2a-2. 9(a-1)^2 - 2(a-1) > 0. (a-1)(9a-9-2) > 0 => (a-1)(9a-11) > 0. So a > 11/9 or a < 1. The statement a < 11/9 is false.

AI explanation

Let the roots of the equation be alpha and beta, which can be written as alpha equals 3 plus m and beta equals 3 plus n, where m and n are both positive. The sum of roots gives 6a equals 6 plus m plus n, which yields a equals 1 plus the quantity (m plus n) divided by 6. The product of roots gives 2 minus 2a plus 9a squared equals 9 plus 3m plus 3n plus mn, and substituting (m plus n) with 6a minus 6 simplifies this to m times n equals 2a squared plus 4a minus 5. For m and n to be strictly positive, both their sum (6a minus 6) and product (2a squared plus 4a minus 5) must be greater than zero, leading to the condition a is greater than 5 divided by 4. Therefore, the statement that a is less than 11 divided by 9 is false.