Answer:
<u>The number is 170</u>
Step-by-step explanation:
Let's solve for x, this way:
x = A number that decreased by 20% of itself, the result is 136
20% = 0.2
x - 0.2x = 136 (Like terms)
0.8x = 136
x = 136/0.8 (Dividing by 0.8 at both sides)
x = 170
Let's prove that x = 170 is correct
170 - 0.2 (170) = 136
170 - 34 = 136
136 = 136
We proved that x = 170 is correct
Answer:
-2
Step-by-step explanation:
becuase -2 - -5=-7
Cos2x = (cosx)^2-(sinx)^2 so if you have the minus before you have to inverse sign: (sinx)^2-(cosx)^2= -cos2x
2x² - 4x - 30
2(x²) - 2(4x) - 2(15)
2(x² - 4x - 15)