giúp mik vs mik cảm ơn nhiều ạ
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beautifully
excitedly
interesting
collected
arrangements
peacefully
excited
different
a,\(x^2-7x+6=x^2-x-6x+6\)
\(=x\left(x-1\right)-6\left(x-1\right)\)
\(=\left(x-6\right)\left(x-1\right)\)
a) x2-7x+6=(x2-x)-(6x-6)=x(x-1)-6(x-1)=(x-6)(x-1)
b) x2-6x+3=(x2-6x+9)-6=(x-3)2-\(\sqrt{6^2}\)=(x-3-\(\sqrt{6}\))(x-3+\(\sqrt{6}\))
c) x2-4x+3=(x2-x)-(3x-3)=x(x-1)-3(x-1)=(x-3)(x-1)
d) 3x2-5x+2=(3x2-3x)-(2x-2)=3x(x-1)-2(x-1)=(3x-2)(x-1)
e) 7x2-x-6=(7x2-7x)+(6x-6)=7x(x-1)+6(x-1)=(7x+6)(x-1)
f) 3x2-5x-8=(3x2+3x)-(8x+8)=3x(x+1)-8(x+1)=(3x-8)(x+1)
g) x2-6x+5=(x2-x)-(5x-5)=x(x-1)-5(x-1)=(x-5)(x-1)
h) x2-2x-3=(x2-2x+1)-4=(x-1)2-22=(x-1-2)(x-1+2)=(x-3)(x+1)
i) x2-x-12=(x2+3x)-(4x+12)=x(x+3)-4(x+3)=(x-4)(x+3)
Lời giải:
ĐKĐB $\Rightarrow \frac{2}{c}=\frac{a+b}{ab}\Rightarrow c(a+b)=2ab$
Khi đó:
$\frac{a}{b}-\frac{a-c}{c-b}=\frac{a(c-b)-b(a-c)}{b(c-b)}=\frac{ac-ab-ab+bc}{b(c-b)}=\frac{c(a+b)-2ab}{b(c-b)}=\frac{2ab-2ab}{b(c-b)}=0$
$\Rightarrow \frac{a}{b}=\frac{a-c}{c-b}$ (đpcm)
1 interested in travelling by plane
2 15 minutes riding his bike to school
3 is made by my mother everymorning
4 take care of her little brother
5 able to speak 2 languages when he was young
6 able to play the piano
7 is played all over VN
8 to play voleyball very well when he was young
9 to go fishing when he was young
10 way to the shopping mall
a: \(x^3+8=\left(x+2\right)\left(x^2-2x+4\right)\)
b: \(27y^3+1=\left(3y+1\right)\left(9y^2-3y+1\right)\)
c: \(x^3-27=\left(x-3\right)\left(x^2+3x+9\right)\)
d: \(x^3-1=\left(x-1\right)\left(x^2+x+1\right)\)
e: \(8x^3+1=\left(2x+1\right)\left(4x^2-2x+1\right)\)
f: \(27x^3+64y^3=\left(3x+4y\right)\left(9x^2-12xy+16y^2\right)\)
g: \(x^3-\dfrac{1}{8}=\left(x-\dfrac{1}{2}\right)\left(x^2+\dfrac{1}{2}x+\dfrac{1}{4}\right)\)
45. The residents find heavy traffic annoying.
46. Mrs Brown is going to have the pipes checked by a plumber next Sunday.
47. This book, which consists of a list of endangered animals, is important.
48. I have difficulty improving my listening English skill.
49. In spite of not having time, they try to eat dinner together.
50. The police officer who gave me the directions how to get home was friendly.
51. They are looking forward to seeing their grandparents this weekend.
52. Unless you try your best, you won’t be successful.
cảm ơn bạn nhiều lắm ạ