Use relationships between roots (e.g., one root is twice the other, difference of roots equals a given value) combined with Vieta's formulas to determine unknown coefficients or parameters.
106-- $\alpha$ and $\beta$ are roots of the equation $x^2 + 6x + a = 0$. If $0 < \alpha < \beta < 0$ and $12\sqrt{2} + 85 = 12\sqrt{2} + 85$, and $3\alpha^2 + 2\beta^2 = 12\sqrt{2} + 85$, what is the value of $a$? (1) $1$ (2) $\dfrac{13}{4}$ (3) $\dfrac{21}{5}$ (4) $2$
Let $a , b , c , p , q$ be real numbers. Suppose $\alpha , \beta$ are the roots of the equation $x ^ { 2 } + 2 p x + q = 0$ and $\alpha , \frac { 1 } { \beta }$ are the roots of the equation $a x ^ { 2 } + 2 b x + c = 0$, where $\beta ^ { 2 } \notin \{ - 1,0,1 \}$. STATEMENT-1 : $\left( p ^ { 2 } - q \right) \left( b ^ { 2 } - a c \right) \geq 0$ and STATEMENT-2 : $b \neq p a$ or $c \neq q a$ (A) STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1 (B) STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1 (C) STATEMENT-1 is True, STATEMENT-2 is False (D) STATEMENT-1 is False, STATEMENT-2 is True
If the equations $x^2 + 2x + 3 = 0$ and $ax^2 + bx + c = 0, a, b, c \in R$, have a common root, then $a : b : c$ is: (1) $1 : 3 : 2$ (2) $3 : 1 : 2$ (3) $1 : 2 : 3$ (4) $3 : 2 : 1$
Let $\alpha , \beta$ be the roots of the equation $x ^ { 2 } - \sqrt { 2 } x + \sqrt { 6 } = 0$ and $\frac { 1 } { \alpha ^ { 2 } } + 1 , \frac { 1 } { \beta ^ { 2 } } + 1$ be the roots of the equation $x ^ { 2 } + a x + b = 0$. Then the roots of the equation $x ^ { 2 } - ( a + b - 2 ) x + ( a + b + 2 ) = 0$ are : (1) non-real complex numbers (2) real and both negative (3) real and both positive (4) real and exactly one of them is positive
Q1 Let $a$ and $b$ be rational numbers and let $p$ be a real number. Consider the quadratic equation $$x ^ { 2 } + a x + b = 0 \tag{1}$$ which has a solution $x = \frac { \sqrt { 5 } + 3 } { \sqrt { 5 } + 2 }$, and consider the inequality $$x + 1 < 2 x + p + 3 . \tag{2}$$ (1) First, we are to find the values of $a$ and $b$. When we rationalize the denominator of $x = \frac { \sqrt { 5 } + 3 } { \sqrt { 5 } + 2 }$, we have $$x = \sqrt { \mathbf { A } } - \mathbf { B }$$ Since this is a solution of equation (1), by substituting this in (1) we have $$- a + b + \mathbf { C } + ( a - \mathbf { D } ) \sqrt { \mathbf { E } } = 0 .$$ Hence we see that $$a = \mathbf { F } \text { and } b = \mathbf { G H } .$$ (2) Next, we are to find the smallest integer $p$ such that both solutions of equation (1) satisfy inequality (2). When we solve inequality (2), we have $$x > - p - 1 .$$ Since both solutions of equation (1) satisfy this, we see that $$p > \sqrt { \mathbf { J } } - \mathbf { K } .$$ Hence the smallest integer $p$ is $\mathbf { L }$.
9. The roots of the equation $2 x ^ { 2 } - 11 x + c = 0$ differ by 2 . The value of $c$ is A $\frac { 105 } { 8 }$ B $\frac { 113 } { 8 }$ C $\frac { 117 } { 8 }$ D $\frac { 119 } { 8 }$
Let k be a positive real number. If the roots of the equation $$2 x ^ { 2 } + k x - 1 = 0$$ have a difference of 2, what is k? A) 1 B) 2 C) $\sqrt { 2 }$ D) $2 \sqrt { 2 }$ E) $\sqrt { 3 }$
Let a be a real number. One root of the equation $$a x ^ { 2 } - 18 x + 18 = 0$$ is 2 times the other. Accordingly, what is a? A) 2 B) 3 C) 4 D) 5 E) 6
Let $m$ and $n$ be two non-zero and distinct real numbers, $$x ^ { 2 } + ( m + 1 ) x + n - m = 0$$ one of the roots of the equation is the number $m - n$. Accordingly, what is the ratio $\frac { \mathbf { n } } { \mathbf { m } }$? A) 2 B) 3 C) 4 D) 5 E) 6
For the equation $x^2 - 2x + c = 0$, the discriminant is also a root of this equation. What is the product of the possible values of the real number $c$? A) 1 B) 2 C) 4 D) $\frac{1}{2}$ E) $\frac{1}{4}$