Answer:
x = -3/4 and 7/2 will be your final answer, but check below for a correction on your work
Step-by-step explanation:
***Your work is incorrect, it should be
2x² - 11x - 21 = 0
you need to subtract an 'x' from both sides, and add 5 to both sides...you added an x to the left side and subtracted a 5 from the left side instead***
I'll solve this so in case you will need help on it too.
Now you'll have
x = (11 ± √[(-11²) - 4(2)(-21)])/([4(2)]
x = (11 ± √289)/8
x = (11 ± 17)/8
x = (11 + 17)/8 = 28/8 = 7/2
or
x = (11 - 17)/8 = -6/8 = -3/4