Question

Which of the following are the roots of the quadratic equation x2 + x - 20 = O by
factorization method ? *
(-5,4)
(5,4)
(10,2)
(-10,2)​

Answer 1

Answer:

Hi ,

Given quadratic equation is

x² + x - 20 = 0

x² + x = 20

x² + 2 × x × 1/2 = 20

x² + 2 × x × 1/2 + ( 1/2 )² = 20 + ( 1/2 )²

( x + 1/2 )² = 20 + 1/4

( x + 1/2 )² = ( 80 + 1 )/4

( x + 1/2 )² = 81/4

x + 1/2 = ± √( 81/4 )

x + 1/2 = ± 9/2

x = -1/2 ± 9/2

x = ( -1/2 + 9/2 ) or x = ( -1/2 - 9/2 )

x = 8/2 or y = -10/2

x = 4 or y= -5

I hope this helps you.

a) is the correct answer

Step-by-step explanation:

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Answer 2

The roots of quadratic equation are (a) (-5,4).

Step-by-step explanation:

We are given a quadratic equation,

$x^{2} +x-20=0$

and we have to find the roots of this given equation by factorization method.

• Calculation for roots of equation

we have ,

$x^{2} +x-20=0$

By using Factorization method we can split  '$x$' as the product of $x^{2}$ and $(-20)$ is equal to the  $+x$ which is in the middle of equation.

so we can write $x$ as $5x-4x$  and the product of $5x*(-4x) = -20x^{2}$.

$x^{2} +5x-4x-20=0$

taking common $x$ from first two terms and $-4$ from last two terms.

$x(x+5)-4(x+5)=0$

$(x-4)(x+5)=0$

so the values of $x$ are 4 and -5.

we get the roots of quadratic equation as (-5,4).