1)(2а-3b)² -(3a+2b)²= (2a)²-2*2a*3b+(3b)²- ( (3a)²+2*3a*2b +(2b)²)=
=4a²+12ab+9b²-9a²-12ab-4b²=(4a²-9a²)+(12ab-12ab)+(9b²-4b²)=
=-5a²+5b²= 5*(b²-a²)
2)(2x-3y)² +(4x+2y)²=( 4x²-2*2x*3y+9y²)+(16x²+2*4x*2y+4y²)=
=(4x²+16x²)+(-12xy+16xy)+(9y²+4y²)= 20x²+4xy+13y²
( Х + 4 ) - ( Х - 3 )( Х - 5 ) = Х + 4 - ( х^2 - 5х - 3х + 15 ) = Х + 4 - х^2 + 8х - 15 = - х^2 + 9х - 11
Х = 1/6
- ( 1/36 ) + ( 9/6 ) - 11 = - ( 1/36 ) + 1 1/2 - 11 = - 11 1/36 + 1 18/36 = - 10 37/36 + 1 18/36 = - 9 19/36
2tg^2x+tgx-3=0 cosx<>0 не равен
(4-x)(2x+3)-(3+x)(1-2x)+6=0
(8x+12-2x²-3x)-(3-6x+x-2x²)+6=0
8x+12-2x²-3x-3+6x-x+2x²+6=0
10x=-18
x=-1,8
Ответ: -1,8