А)
18,28*1,2=21,936~22
18,28/1,2=15,2333..~15
б)
0,36*7,5=2,7~3
0,36/7,5=0,048~0,05
1) 2a+bc+2b+ac=(2a+ac)+(2b+bc)=a(2+c)+b(2+c)=(a+b)(2+c)
2) 3mx-my+3nx-ny=m(3x-y)+n(3x-y)=(m+n)(3x-y)
3) ab-ac-5b+5c=(ab-ac)-(5b-5c)=a(b-c)-5(b-c)=(b-c)(a-5)
4) ax+bx-ay-by+az+bz=(ax-ay+az)+(bx-by+bz)=a(x-y+z)+b(x-y+)=(a+b)(x-y+z)
5) a+b+c(a+b)=(1+c)(a+b)
6) m-n+p(m-n)=(1+p)(m-n)
7) x+3a(x+y)+y=(1+3a)(x+y)
8) x+2a(x-y)-y=(1+2a)(x-y)
9) 2m(m-n)+m-n=(2m+1)(m-n)
10) 4q(p-1)+(p-1)=(4q+1)(p-1)
11) 2m(m-n)+n-m=2m(m-n)-(m-n)=(2m-1)(m-n)
12) 4q(p-1)+1-p=4q(p-1)-(p-1)=(4q-1)(p-1)
13) ab+bc-2ad-2bd=(a+b)(1-2d)
14) ac-3bd+ad-3bc=(ac+ad)-(3bc+3bd)=a(c+d)-3b(c+d)=(a-3b)(c+d)
15) 2bx-3ay-6by+ax=(2bx-6by)+(ax-3ay)=2b(x-3y)+a(x-3y)=(2b+a)(x-3y)
16) 5ay+3bx+ax-15by=(x-5y)(3b+a)
17) 18a^2-27ab+14ac-21bc=(9a+7c)(2a-3b)
18) 10x^2+10xy+5x+5y=10x(x+y)+5(x+y)=(10x+5)(x+y)
19) 35ax+24xy-20ay-42x^2=(35ax-20ay)-(42x^2-24xy)=5a(7x-4y)-6x(7x-4y)=(5a-6x)(7x-4y)
20) 48xz^2+32xy^2-15yz^2-10y^3=(16x-5y)(3z^2+2y^2)
(2x+3y=10
<span>(x-2y=-9
1) </span>x-2y=-9
x=-9+2y
2)2(-9+2y)+3y=10
-18+4y+3y=10
7y=10+18
7y=28
y=4
3) x=-9+2*4
x=-1
1) (m²-4n)²-(m²-2n)²= (m²-4n-m²+2n)(m²-4n+m²-2n)=-2n(2m²-6n)=12n²-4m²n.
a²-b²=(a-b)(a+b)
a=(m²-4n)²
b=(m²-2n)²
2) (x-2y)²+4(x-2y)+4=x²-4xy+4y²+4x-8y+4
(a-b)²=a²-2×a×b+b²
a=x
b=2y
(x-2y)²+4(x-2y)+4=((x-2y)+2)²
a²+2×a×b+b²=(a+b)²
a=(x-2y)
b²=4=>√b²=√4=>b=2
3) (m²-4n)²-(m²-2n²)=(m²)²-2×m²×4n+(4n)²-m²+2n²=m⁴-8m²n+16n²-m²+2n²=m⁴-m²-8m²n+18n²
(a-b)²=a²-2×a×b+b²
a=m²
b=4n
<span> (2х+1)*(х-4)
2х*х+2х*(-4)+1*х+1*(-4)
2х</span>²-8х+х-4
2х²-7х-4=0
д=(-7)²-4*2*(-4)=49+32=81
х1=(7+√81)/2*2=16/4=4
х2=(7-√81)/2*2=-2/4=-0,5
Ответ: х1=4,х2=-0,5
