How do you solve \[ - 2{x^2} = 2x - 4\] ?
Answer
625.8k+ views
Hint: In this question, a polynomial equation of degree 2 is given to us as 2 is the highest exponent in the given equation, hence it is a quadratic equation and has exactly two solutions. Solutions of an equation are defined as the values of the x for which the given function has a value zero or when we plot this function on the graph, we see that the solutions of this function are the points on which the y-coordinate is zero, thus they are simply the x-intercepts.
Complete step-by-step solution:
We are given that
\[ - 2{x^2} = 2x - 4\]
Now we will take all the terms to one side such that they are equal to zero and then take 2 and negative sign common to convert it into standard form –
$
- 2{x^2} - 2x + 4 = 0 \\
\Rightarrow {x^2} + x - 2 = 0 \\
$
The obtained equation is in standard form, on factorization we get –
$
{x^2} + x - 2 = 0 \\
\Rightarrow {x^2} + 2x - x - 2 = 0 \\
\Rightarrow x(x + 2) - 1(x + 2) = 0 \\
\Rightarrow (x - 1)(x + 2) = 0 \\
\Rightarrow x - 1 = 0,\,x + 2 = 0 \\
\Rightarrow x = 1,\,x = - 2 \\
$
Hence the factors of the equation \[ - 2{x^2} = 2x - 4\] are $x - 1 = 0$ and $x + 2 = 0$ .
Note: The standard form of a quadratic equation is $a{x^2} + bx + c = 0$ . To find the factors of the given equation, we compare the given equation and the standard equation and get the values of a, b and c. Then we will try to write b as a sum of two numbers such that their product is equal to the product of a and c, that is, ${b_1} \times {b_2} = a \times c$ , this method is known as factorization. We find the value of ${b_1}$ and ${b_2}$ by hit and trial. We move to some other methods like quadratic formula, graphing, and completing the square method, if we are not able to solve an equation by factorization.
Complete step-by-step solution:
We are given that
\[ - 2{x^2} = 2x - 4\]
Now we will take all the terms to one side such that they are equal to zero and then take 2 and negative sign common to convert it into standard form –
$
- 2{x^2} - 2x + 4 = 0 \\
\Rightarrow {x^2} + x - 2 = 0 \\
$
The obtained equation is in standard form, on factorization we get –
$
{x^2} + x - 2 = 0 \\
\Rightarrow {x^2} + 2x - x - 2 = 0 \\
\Rightarrow x(x + 2) - 1(x + 2) = 0 \\
\Rightarrow (x - 1)(x + 2) = 0 \\
\Rightarrow x - 1 = 0,\,x + 2 = 0 \\
\Rightarrow x = 1,\,x = - 2 \\
$
Hence the factors of the equation \[ - 2{x^2} = 2x - 4\] are $x - 1 = 0$ and $x + 2 = 0$ .
Note: The standard form of a quadratic equation is $a{x^2} + bx + c = 0$ . To find the factors of the given equation, we compare the given equation and the standard equation and get the values of a, b and c. Then we will try to write b as a sum of two numbers such that their product is equal to the product of a and c, that is, ${b_1} \times {b_2} = a \times c$ , this method is known as factorization. We find the value of ${b_1}$ and ${b_2}$ by hit and trial. We move to some other methods like quadratic formula, graphing, and completing the square method, if we are not able to solve an equation by factorization.
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