Cos0°+sin90°-tg180°-cos60°вычислите

cos0°+sin90°-tg180°-cos60°=1+1-0-0,5=1,5

(tg180°=tg0°=0,cos60°=sin30°=0,5)

x-28/(x-1)=4

x*(x-1)-28=4*(x-1)

x^2-x-28=4x-4

x^2-5x-24=0

d=b^2-4ac=121

x1,2=(-b±sqrt(d))/2a

x1=(5-11)/2=-3

x2=(5+11)/2=8

2a=ab-b2

2a-ab=b2

a(2-b)=b2

a=b2/(2-b)