-0.2k = -15 ( then divide -0.2k on both sides)
The answer is then k= 75
cos (2x) = cos x
2 cos^2 x -1 = cos x using the double angle formula
2 cos ^2 x -cos x -1 =0
factor
(2 cos x+1) ( cos x -1) = 0
using the zero product property
2 cos x+1 =0 cos x -1 =0
2 cos x = -1 cos x =1
cos x = -1/2 cos x=1
taking the arccos of each side
arccos cos x = arccos (-1/2) arccos cos x = arccos 1
x = 120 degrees x=-120 degrees x=0
remember you get 2 values ( 2nd and 3rd quadrant)
these are the principal values
now we need to add 360
x = 120+ 360n x=-120+ 360n x = 0 + 360n where n is an integer
Answer:
D
Step-by-step explanation:
If (x - 5) is a factor of P(x) then P(5) = 0 ← Factor theorem
Given
P(x) = x³ - 5x² - x + 5, then
P(5) = 5³ - 5(5)² - 5 + 5 = 125 - 125 - 5 + 5 = 0
Since P(5) = 0 then (x - 5) is a factor of P(x)
Answer:
-2.5
Step-by-step explanation:
-2 and 1/2 = 1
-2.50 x 1 = -2.5
Answer:
x= -7, y= -5 and
x= 2, y= 13
This may also be written as (-7, -5) and (2, 13).
Step-by-step explanation:
Start by labelling the two given equations:
y= x² +7x -5 -----(1)
2x -y= -9 -----(2)
Let's solve by substitution!
Making y the subject of formula in equation (2):
From (2): y= 2x +9 -----(3)
Substitute (3) into (1):
2x +9= x² +7x -5
x² +7x -5 -2x -9= 0
x² +5x -14= 0
Factorise:
(x +7)(x -2)= 0
x +7= 0 or x -2= 0
x= -7 or x= 2
Find the respective values of y.
Substitute into (1):
y= (-7)² +7(-7) -5 or y= (2)² +7(2) -5
y= 49 -49 -5 or y= 4 +14 -5
y= -5 or y= 13
Thus, the solutions are (-7, -5) and (2, 13).