q=a2/a1=a3/a2=a4/a3=-----------
a1=12,a2=4,a3=4/3,............
q=4/12=1/3
q=1/3
=====
0.25x+2*0.5*1.6*x*y+2.56y=0.25x+1.6xy+2.56y
(x-x₁)(x-x₂)=(x-√3)(x-√5)=x²-x√5-x√3+√15=x²-(√5+√3)x+√15
<u>4х + 4</u> + 5 = <u> 9х</u> Общий знаменатель 56
8 7
28х + 28 + 280 = 72х
28х - 72х = - 280 - 28
- 44х = - 308
44х = 308
<u> х = 7</u>