Answer:
C. (x + 4)(x + 5).
Step-by-step explanation:
We need 2 numbers whose product is + 20 and whose sum is + 9.
They are + 5 and + 4 , so
x2 + 9x +20
= (x + 4)(x + 5).
Answer:
(3/2, 6)
Step-by-step explanation:
y = 4x
8x + y = 18
this says y is 4x so you can replace y with 4x
8x + 4x = 18
12x = 18
/12 /12
x = 3/2
now sub x into y = 4(3/2)
y = 12/2
y = 6
Answer:
The answer is 1.3, 1 3/10
Answer: cos(x)
Step-by-step explanation:
We have
sin ( x + y ) = sin(x)*cos(y) + cos(x)*sin(y) (1) and
cos ( x + y ) = cos(x)*cos(y) - sin(x)*sin(y) (2)
From eq. (1)
if x = y
sin ( x + x ) = sin(x)*cos(x) + cos(x)*sin(x) ⇒ sin(2x) = 2sin(x)cos(x)
From eq. 2
If x = y
cos ( x + x ) = cos(x)*cos(x) - sin(x)*sin(x) ⇒ cos²(x) - sin²(x)
cos (2x) = cos²(x) - sin²(x)
Hence:The expression:
cos(2x) cos(x) + sin(2x) sin(x) (3)
Subtition of sin(2x) and cos(2x) in eq. 3
[cos²(x)-sin²(x)]*cos(x) + [(2sen(x)cos(x)]*sin(x)
and operating
cos³(x) - sin²(x)cos(x) + 2sin²(x)cos(x) = cos³(x) + sin²(x)cos(x)
cos (x) [ cos²(x) + sin²(x) ] = cos(x)
since cos²(x) + sin²(x) = 1
