Answer:
-x² - 10x -21 = 0
x² +10x +21 = 0
x² + 7x + 3x + 21 = 0
x ( x+7) + 3 (x+7) = 0
(x+3) (x+7) = 0
when (x+3) = 0,
x = -3
Again,
(x+7) = 0
x = -7
7 and 3
Step-by-step explanation:
-b +/- sqrt(b^2+4ac)/2a
10 +/- sqrt(100-84)/2
10 +/- 4/2
Your answer is correct
(2^5/4)² = 4^5/2 = √4^5
