Question

$5 {x}^{2} - 16x - 21$

Answer 1

5 x² - 16 x - 21 = 0

==> 5 x² + 5 x -21 x - 21 = 0

==> 5 x ( x + 1 ) - 21 ( x + 1 ) = 0

==> ( 5 x - 21 ) ( x + 1 ) = 0

Either :

5 x = 21

==> x = 21 / 5

or ,

x + 1 = 0

==> x = -1

The values of x are - 1 and 21 / 5

Hope it helps you:-)

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Answer 2

Hey mate
Here is your answer in image