Question

NEED HELP ASAPI need answers please ​

Answer 1

Answer:

Step-by-step explanation:

10) Cos (x-y) = cos x cos y + sin x sin y

cos 4x cox 3x + sin 4x sin 3x = Cos (4x - 3x)

  = cos x

11) = 2*(1² + 2) + 2*(2² + 2²)

  = 2*3 + 2*(4+4)

= 6 + 2*8

= 6 + 16

= 22

12) (3) 4x² - 3x  - 8 = 0

Reason:  

Sum of roots = - Coefficient of x/coefficient of x² = -(-3)/4 = 3/4

Product of roots = constant / coefficient of x² = -8/4 = -2

Answer 2

Should’ve listened in class buddy