Question

8 x square - 22 x minus 21 equal to zero solve it​

Answer 1

it is given that, 8x² - 22x - 21 = 0

first of all, we should check, given polynomial has real roots or not.

find discriminant , D = b² - 4ac

= (-22)² - 4(-21)(8) = 484 + 672 = 1156 = (34)² > 0, discriminant is positive so, given quadratic polynomial has real roots.

now let's start to solve it.

8x² - 22x - 21 = 0

or, 8x² - 28x + 6x - 21 = 0

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

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

or, x = -3/4 and 7/2

hence, zeros of given quadratic are ; -3/4 and 7/2.

Answer 2

Answer:

Solve 8 x square - 22 x minus 21 equal to zero

Solve  8x ² - 22x - 21 = 0

x= 7/2 or -3/4

Step-by-step explanation:

8x ² - 22x - 21

We can use the quadratic formula to solve this equation

The quadratic formula is given as :

For an equation ax² + bx + c

x will be given by:

x = {-b ± √(b² - 4ac)}/2a

In this case: a = 8

                  b = -22

                  c = 21

Substitute the values in the eqaution given above to find the value of x

x = {-b ± √(b² - 4ac)}/2a

x = {-(-22) ± √(-22² - (4 × 8 × -21)}/2 × 8

x = {22± √(484 - (-672)} / 16

x = (22 ± √1156) / 16

x = (22 ± 34) / 16

x = (22 + 34) / 16   or (22 - 34) /16

x = 56 / 16  or -12/16

x = 7/2 or - 3/4