( х + 2 )² - ( х - 5 )² = х² + 4х + 4 - ( х² - 10х + 25 ) = х² + 4х + 4 - х² + 10х - 25 = <em><u>14х - 21</u></em><em>.</em>
(2-b)/b +(b-3)/3b²=(3b(2-b)+b-3)/3b²=(6b-3b²+b-3)/3b² =(7b-3b²-3)/3b²
(3c+9)/6c * 2c^4/(c+3)=(3(c+3) * 2c^4)/(6c*(c+3))=(6c^4(c+3))/(6c(c+3))=c³
(x²-y²)/6y : (x-y)²=((x-y)(x+y))/(6y(x-y)(x-y)) =(x+y)/(6y(x-y))
<span>2x-8x=0
-6x = 0
x = 0 : -6
x =0</span>