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góc ACK = 900- góc KAC=900-550=350
góc M2=900-góc ACK=900-350=55 độ
góc BMC = 180 độ - góc M2=1800-550=125 độ
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a, \(3x+7x^2+5+2x-7x^2\ge0\Leftrightarrow5x+5\ge0\Leftrightarrow x\ge-1\)
b, \(12x\ge-16\Leftrightarrow x\ge-\dfrac{4}{3}\)
c, \(\dfrac{5x-1-6}{6}-\dfrac{4\left(x+1\right)}{3}\le0\)
\(\Leftrightarrow\dfrac{5x-7-8\left(x+1\right)}{6}\le0\Rightarrow-3x-15\le0\Leftrightarrow x\le-5\)
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19. 3x2-4x+1
= 3x2-3x-x+1
= (3x2-3x)-(x-1)
= 3x(x-1)-(x-1)
= (3x-1)(x-1)
20.3x2+4x-7
= 3x2+3x-7x-7
= (3x2+3x)-(7x+7)
= 3x(x+1)-7(x-1)
= (3x-7)(x-1)
21.3x2+7x-6
= 3x2+9x-2x-6
= (3x2+9x)-(2x+6)
= 3x(x+3)-2(x+3)
= (3x-2)(x+3)
22.3x2+3x-6
= 3x2+6x-3x-6
=(3x2+6x)-(3x+6)
= 3x(x+2)-3(x+2)
=(3x-3)(x+2)
= 3(x-1)(x+2)
23. 3x2-3x-6
=(3x2-6x)+(3x-6)
=3x(x-2)+3(x-2)
=(3x+3)(x-2)
= 3(x+1)(x-2)
24.6x2-13x+6
= 6x2-9x-4x+6
= (6x2-9x)-(4x-6)
=3x(2x-3)-2(2x-3)
=(3x-2)(2x-3)
25.6x2+13x+6
= 6x2+9x+4x+6
= (6x2+9x)+(4x+6)
=3x(2x+3)+2(2x+3)
=(3x+2)(2x+3)
26. 6x2+15x+6
= (6x2+12x)+(3x+6)
= 6x(x+2)+3(x+2)
=(6x+3)(x+2)
=3(2x+1)(x+2)
27. 6x2-15x+6
= (6x2-12x)-(3x-6)
= 6x(x-2)-3(x-2)
=(6x-3)(x-2)
=3(2x-1)(x-2)
28. 6x2+20x+6
= (6x2+18x)+(2x+6)
= 6x(x+3)+2(x+3)
= (6x+2)(x+3)
= 2(3x+1)(x+3)
29.6x2-20x+6
= (6x2-18x)-(2x-6)
= 6x(x-3)+2(x-3)
= (6x-2)(x-3)
= 2(3x-1)(x-3)
30.6x2+12x+6
= (6x2+6x)+(6x+6)
= 6x(x+1)+6(x+1)
= (6x+6)(x+1)
= 6(x+1)(x+1)
= 6(x+1)2
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a: \(4x^2-4x\)
\(=4x\cdot x-4x\cdot1\)
\(=4x\left(x-1\right)\)
b: \(x^2-2xy+y^2-4\)
\(=\left(x-y\right)^2-2^2\)
\(=\left(x-y-2\right)\left(x-y+2\right)\)
Bài 1.
a) ĐKXĐ: \(x^2-1\ne0\Leftrightarrow x\ne\pm1\)
b) Để \(B=2\) thì \(\dfrac{x^2+2x+1}{x^2-1}=2\)
\(\Leftrightarrow\dfrac{\left(x+1\right)^2}{\left(x-1\right)\left(x+1\right)}=2\)
\(\Leftrightarrow\dfrac{x+1}{x-1}=2\)
\(\Rightarrow x+1=2x-2\)
\(\Leftrightarrow2x-x=1+2\)
\(\Leftrightarrow x=3\left(tm\right)\)
Bài 2.
a) ĐKXĐ: \(x+2\ne0\Leftrightarrow x\ne-2\)
b) Với \(x=1\Rightarrow\) thoả mãn đk \(x\ne-2\)
Ta có: \(C=\dfrac{x^2+4x+4}{x+2}=\dfrac{\left(x+2\right)^2}{x+2}=x+2\)
Thay \(x=1\) vào \(C\), ta được:
\(C=1+2=3\)
c) Để \(C=1\) thì \(x+2=1\Leftrightarrow x=-1\left(tm\right)\)
\(\text{#}Toru\)