1) (3x+2)^2+(4x+1)(4x-1)=(5x-1)^2
9x^2 + 12x + 4 + (16x^2 - 1) = 25x^2 - 10x + 1
9x^2 + 12x + 4 + 16x^2 - 1 - 25x^2 - 10x = 1
22x = -2
x = -1/11
2) 234^2-233^2= (234-233)(234+233)= 1*467 = 467
3) 139^2+2*139*61+61^2 = (139+61)^2 = 200^2 = 40 000
4) 159^2-2*159*59+59^2 = (159-59)^2 = 100^2 = 10 000
B1 = 2
b2 = b1 - 3 = 2 - 3 = - 1
b3 = b2 - 3 = - 1 - 3 = - 4
b4 = b3 - 3 = - 4 - 3 = - 7
b5 = b4 - 3 = - 7 - 3 = - 10
b6 = b5 - 3 = - 10 - 3 = - 13
Cosx <
arccos(
) + 2πn < x < 2π - arccos(
) + 2πn
+ 2πn < x < 2π -
+ 2πn
+ 2πn < x <
+ 2πn
[!] n ∈ Z