Photomath - помогает тебе
1) y=(6-2x)
2x(6-2x)=5
12x-4x²-5=0|×(-1)
4x²-12x-5=0
D=√((-12)²-4*4*(-5))=√(144+80)=√224
x1=(-(-12)+√224)/2*4=(12+√224)/8=(12+4√14)/8
x2=(-(-12)-√224)/8=(12-√224)/8=(12-4√14)/8
y=5/2x
y1=5/2x1=5/2*(12+4√14)/8=5/8(3+√14)/8=5/(3+√14);
y2=5/2x2=5/2(12-4√14)/8=5/8(3-√14)/8=5/(3-√14).
2) x=(2+2y)
2y(2+2y)=3
4y+4y²-3=0
D=√(4²-4*4(-3))=√(16+48)=√64=8
y1=(-4+8)/2*4=4/8=0,5
y2=(-4-8)/8=-12/8=-1,5
x1=(2+2y1)=2+2*0,5=2+1=3
x2=(2+2y2)=2+2*(-1,5)=2-3=-1
<span>4,4 < a < 4,5
6,3 < b < 6,4</span>
10,7<a+b<10,9
21,4<2(a+b)<21,8
27,72<a*b<28,8
а) -0,28*4/7+5\7:2 6/7 = -28/100 * 4/7 + 5/7÷26/7 = - 4/25 + 5/26 =-104+ 125 / 650 = 21/ 600 = 7/300
б) 5/6*(-0,3) - 4/5:1 1/15 = 5/6 * (-3/10) - 4/5 ÷ 11/15 = -1/ 4 - 12/11 = -11- 48 / 44 = -59/44 = - 1 целая 15/44
1) (x-2)²-4 = ((x-2)-2)<span>((x-2)+2)
2) (b+7)² - 100с² = ((b+7)-10c)</span><span><span>((b+7)+10c)
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3) 121-(b+7)² = </span>(11-(b+7))(11+(b+7))