Question

Solve the quadratic equation 3x - 5x - 7 = 0
Give your answers to 3 significant figures.

Answer 1

Answer:

The solutions of $3\cdot x^{2}-5\cdot x -7 = 0$ are $x_{1} \approx 2.573$ and $x_{2} \approx -0.907$.

Step-by-step explanation:

The statement is incomplete. The complete description will be shown below:

Solve the quadratic equation $3\cdot x^{2}-5\cdot x -7 = 0$. Give your answers to 3 significant figures.

From Algebra we know that second order polynomials of the form $a\cdot x^{2}+b\cdot x + c = 0$, $a \ne0$ can be solved anatically by means of the Quadratic Formula, that is:

$x = \frac{-b\pm\sqrt{b^{2}-4\cdot a\cdot c}}{2\cdot a}$ (1)

Where $a$, $b$, $c$ are coefficients of the given polynomial.

If we know that $a = 3$, $b = -5$ and $c = -7$, then the roots of the polynomial are:

$x_{1,2} = \frac{5\pm \sqrt{(-5)^{2}-4\cdot (3)\cdot (-7)}}{2\cdot (3)}$

$x_{1,2} = \frac{5}{6}\pm \frac{\sqrt{109}}{6}$

That is,

$x_{1} \approx 2.573$ and $x_{2} \approx -0.907$

The solutions of $3\cdot x^{2}-5\cdot x -7 = 0$ are $x_{1} \approx 2.573$ and $x_{2} \approx -0.907$.