А) 9х^2 - 1 - 9х^2 + 12x - 4 = 0
12x - 5 = 0
x = 0.417
Б) 4x^2 - 12x + 9 - 8x - 4x^2 = 11
-20x = 2
x = -0.1
B) x + 25x^2 + 20 + 4 = 25 + 25x^2
21x = 21
x = 1
Г) 16х^2 - 9 - 16х^2 + 2 = 0
-7 не = О
A1=-6 a2=-2
d=a2-a1=-2+6=4
a16=a1+15d=-6+60=54
Ответ:
Объяснение:
x²+8x-y²-6y+7=x²+2*4*x-y²-2*3*y+16-9=(x²+2*x*4+4²)-(y²+2*y*3+3²)=
=(x+4)²-(y+3)²=(x+4+y+3)*(x+4-y-3)=(x+y+7)*(x-y+1).
1)x-4y=-1
2)3x-y=8
1)x=4y-1
2)3(4y-1)-y=8
1)x=4y-1
2)11y=11
1)x=4y-1
2)y=1
1)x=4*1-1=3
2)y=1