Question

solve the following quadratic equation by factorisation method : 8x²-22x-21=0

Answer 1

$\huge\bf\orange{Hey There!!!}$



Given quadratic equation

$8x {}^{2} - 22x - 21 = 0$

On comparing with ax^2 + bx + c = 0 we get

a = 8

b = - 22

c = - 21

We know that the product of 'a' and 'c' should be the difference or sum of the middle term.

Let's solve

$8x {}^{2} - 22x - 21 = 0$


$= > 8x {}^{2} + 6x - 28x - 21 = 0 \\ \\ = > 2x(4x + 3) - 7(4x + 3) = 0 \\ \\ = > (4x + 3)(2x - 7) = 0 \\ \\ = > 4x + 3 = 0 \: \: or \: \: 2x - 7 = 0 \\ \\ = > x = - \frac{3}{4} \: \: or \: \: x = \frac{ 7}{2} .$


Hope it helps!

Answer 2

Hi mate !!

Here is your answer :

Question : Solve the following quadratic equation by Factorisation method : 8x² - 22x - 21 = 0.

GIVEN equation in the form of quadratic equation .

ax^2 + bx + c = 0

the given equation also in the form of standard of a quadratic equation.


Given equation : 8x² - 22x - 21 = 0

Split the middle term , we get

8x² - 28x + 6x - 21 = 0

4x ( 2x - 7 ) + 3 ( 2x - 7 ) = 0

Taking ( 2x - 7 ) as commom , we get

( 2x - 7 ) ( 4x + 3 ) = 0

Now , By zero product rule , we get

( 2x - 7 ) = 0 or ( 4x + 3 ) = 0

2x = 7 or 4x = -3

x = 7/2 or x = -3/4.

Hence,

7/2 and -3/4 are the two zeroes of the given quadratic equation.

Hope it helps you ♥

By Rishi403.

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