А1. (4у^2–5у–2)*5у^2=20у^4-25у^3-
-10у^2 (3)
А2. 7х^2–3х(6–2х^2)=7х^2–18х+
+6х^3 (4)
А3. 1,5х(4–6х)–3х(х–4)=3х(2–3х)–
–3х(х–4)=3х(2–3х–х+4)=3х(6–4х)=
=3*1(6–4*1)=6 (2)
А4. 4b(b+9)–3(b^2+12b)–b^2+7=
=4b^2+36b–3b^2–36b–b^2+7=7 (3)
B1. 0,3x^2–9x=0
0,3x(x–30)=0
0,3x=0; x–30=0
x=0; x=30
C1. 0,4x^2(5+3x)+0,2x=0,2x^2(6x–3)
0,4x^2(5+3x)+0,2x–0,2x^2(6x–3)=0
0,2x(2x(5+3x)+1–x(6x–3)=0
0,2x(10x+6x^2+1–6x^2+3x)=0
0,2x=0; 13x+1=0;
x=0; 13x=–1;
x=–1/13;
Ответ: меньший корень уравнения -1/13