40 is the correct answer. Hope this helps :)
Sorry, what grade is that for? might need to learn that right away
Answer:
Bases change red litmus into blue and bases have a slippery and soapy texture. Therefore, we can conclude that out of the given options, one way to test whether an unknown solution is acidic or basic is to check whether the solution has a slippery feel
Step-by-step explanation:
There’s an app called photomath, thank me later
Rearrange the equation by writing
x² + x - 90 = 0
x² + x = 90
x² + x + 1/4 = 90 + 1/4
Recall that (a + b)² = a² + 2ab + b². Then
x² + 2 • x/2 + (1/2)² = 361/4
(x + 1/2)² = 361/4
x + 1/2 = ± √(361/4)
x = -1/2 ± 19/2
x = 9 or x = -10
