How do you factor $ - 3{x^2} + 2x + 2$?
Answer
624k+ views
Hint: First take $ - 3$ common from the given equation. Next, compare the given quadratic equation to the standard quadratic equation and find the value of numbers $a$, $b$ and $c$ in the given equation. Then, substitute the values of $a$, $b$ and $c$ in the formula of discriminant and find the discriminant of the given equation. Finally, put the values of $a$, $b$ and $D$ in the roots of the quadratic equation formula and get the desired result.
Formula used: The quantity $D = {b^2} - 4ac$ is known as the discriminant of the equation $a{x^2} + bx + c = 0$ and its roots are given by
$x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$ or $x = \dfrac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}$
Complete step-by-step solution:
It is given that the expression of $ - 3{x^2} + 2x + 2$
We know that an equation of the form $a{x^2} + bx + c = 0$, $a,b,c,x \in R$, is called a Real Quadratic Equation.
The numbers $a$, $b$ and $c$ are called the coefficients of the equation.
The quantity $D = {b^2} - 4ac$ is known as the discriminant of the equation $a{x^2} + bx + c = 0$ and its roots are given by
$x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$ or $x = \dfrac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}$
So, first we will take $ - 3$ common from the given equation.
$ - 3{x^2} + 2x + 2 = - 3\left( {{x^2} - \dfrac{2}{3}x - \dfrac{2}{3}} \right)$
Next, compare ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$ quadratic equation to standard quadratic equation and find the value of numbers $a$, $b$ and $c$.
Comparing ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$ with $a{x^2} + bx + c = 0$, we get
$a = 1$, $b = - \dfrac{2}{3}$ and $c = - \dfrac{2}{3}$
Now, substitute the values of $a$, $b$ and $c$ in $D = {b^2} - 4ac$ and find the discriminant of the given equation.
$D = {\left( { - \dfrac{2}{3}} \right)^2} - 4\left( 1 \right)\left( { - \dfrac{2}{3}} \right)$
After simplifying the result, we get
$D = \dfrac{{28}}{9}$
Which means the given equation has real roots.
Now putting the values of $a$, $b$ and $D$ in $x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$, we get
$x = \dfrac{{\dfrac{2}{3} \pm \dfrac{{2\sqrt 7 }}{3}}}{{2 \times 1}}$
Divide numerator and denominator by $2$, we get
$x = \dfrac{1}{3} \pm \dfrac{{\sqrt 7 }}{3}$
So, $x = \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}$ and $x = \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}$are roots of equation ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$.
Therefore, the trinomial $ - 3{x^2} + 2x + 2$ can be factored as $ - 3\left( {x - \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}} \right)\left( {x - \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}} \right)$.
Note: In above question, it should be noted that we get $x = \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}$and $x = \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}$ as the roots of equation${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$.
No other roots will satisfy the condition.
If we take wrong factors, then we will not get a trinomial on their product. So, carefully find the roots.
Formula used: The quantity $D = {b^2} - 4ac$ is known as the discriminant of the equation $a{x^2} + bx + c = 0$ and its roots are given by
$x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$ or $x = \dfrac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}$
Complete step-by-step solution:
It is given that the expression of $ - 3{x^2} + 2x + 2$
We know that an equation of the form $a{x^2} + bx + c = 0$, $a,b,c,x \in R$, is called a Real Quadratic Equation.
The numbers $a$, $b$ and $c$ are called the coefficients of the equation.
The quantity $D = {b^2} - 4ac$ is known as the discriminant of the equation $a{x^2} + bx + c = 0$ and its roots are given by
$x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$ or $x = \dfrac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}$
So, first we will take $ - 3$ common from the given equation.
$ - 3{x^2} + 2x + 2 = - 3\left( {{x^2} - \dfrac{2}{3}x - \dfrac{2}{3}} \right)$
Next, compare ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$ quadratic equation to standard quadratic equation and find the value of numbers $a$, $b$ and $c$.
Comparing ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$ with $a{x^2} + bx + c = 0$, we get
$a = 1$, $b = - \dfrac{2}{3}$ and $c = - \dfrac{2}{3}$
Now, substitute the values of $a$, $b$ and $c$ in $D = {b^2} - 4ac$ and find the discriminant of the given equation.
$D = {\left( { - \dfrac{2}{3}} \right)^2} - 4\left( 1 \right)\left( { - \dfrac{2}{3}} \right)$
After simplifying the result, we get
$D = \dfrac{{28}}{9}$
Which means the given equation has real roots.
Now putting the values of $a$, $b$ and $D$ in $x = \dfrac{{ - b \pm \sqrt D }}{{2a}}$, we get
$x = \dfrac{{\dfrac{2}{3} \pm \dfrac{{2\sqrt 7 }}{3}}}{{2 \times 1}}$
Divide numerator and denominator by $2$, we get
$x = \dfrac{1}{3} \pm \dfrac{{\sqrt 7 }}{3}$
So, $x = \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}$ and $x = \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}$are roots of equation ${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$.
Therefore, the trinomial $ - 3{x^2} + 2x + 2$ can be factored as $ - 3\left( {x - \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}} \right)\left( {x - \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}} \right)$.
Note: In above question, it should be noted that we get $x = \dfrac{1}{3} + \dfrac{{\sqrt 7 }}{3}$and $x = \dfrac{1}{3} - \dfrac{{\sqrt 7 }}{3}$ as the roots of equation${x^2} - \dfrac{2}{3}x - \dfrac{2}{3}$.
No other roots will satisfy the condition.
If we take wrong factors, then we will not get a trinomial on their product. So, carefully find the roots.
Recently Updated Pages
A boat goes 24 km upstream and 28 km downstream in class 10 maths CBSE

Write any three differences between metals and nonmetals class 10 social science CBSE

Amit standing on a horizontal plane finds a bird flying class 10 maths CBSE

Two circles of radii 5 cm and 3 cm intersect at two class 10 maths CBSE

Solve the following i John and Jivanti together have class 10 maths CBSE

What is the relation between orthocenter circumcentre class 10 maths CBSE

Trending doubts
Explain the Treaty of Vienna of 1815 class 10 social science CBSE

Which country is known as "The land of Fire and Ice"?

10 examples of evaporation in daily life with explanations

What is the full form of POSCO class 10 social science CBSE

Make a sketch of the human nerve cell What function class 10 biology CBSE

Differentiate between Xylem and phloem class 10 biology CBSE

