Answer:
4a + 20
Step-by-step explanation:
Using the distributive property, multiply each term in the parenthesis by 4
4(a + 5)
= (4 × a) + (4 × 5) = 4a + 20
Answer:
d) 
Step-by-step explanation:
b) 
This expression is not equivalent, as the original expression, 
, has 9 multiplied to 
instead of y. You can interchange values like this when it comes to addition, but not multiplication.
c) 
This expression is also not equivalent. After opening up the parentheses, it would again result in y being multiplied to .
d)
This expression is equivalent, as 9 and are still being multiplied together and y is added to the product. We can actually rearrange this to look like the original expression:
I hope this helps!
Answer:
x = 90°
Step-by-step explanation:
Using the identity
cos²x = 1 - sin²x
Given
cos²x - sin x + 1 = 0
1 - sin²x - sin x + 1 = 0
- sin²x - sin x + 2 = 0 ← quadratic equation in sin x ( multiply through by - 1 )
sin²x + sin x - 2 = 0 ← in standard form
(sinx + 2)(sinx - 1) = 0 ← in factored form
Equate each factor to zero and solve for x
sinx + 2 = 0 ⇒ sinx = - 2 ← has no solution as - 1 ≤ x ≤ 1
sinx - 1 = 0 ⇒ sinx = 1 ⇒ x = 90°
solution is x = 90°
The sign would be NEGATIVE
