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Mình làm 1 bài thôi nhé
Bài 5
\(a.1-2y+y^2=\left(1-y\right)^2\)
\(b.\left(x+1\right)^2-25=\left(x+1\right)^2-5^2=\left(x-4\right)\left(x+6\right)\)
\(c.1-4x^2=1-\left(2x\right)^2=\left(1-2x\right)\left(1+2x\right)\)
\(d.27+27x+9x^2+x^3=3^3+3.3^3.x+3.3.x^2+x^3=\left(3+x\right)^3\)
\(f.8x^3-12x^2y+6xy-y^3=\left(2x\right)^3-3.\left(2x\right)^2.y+3.2x.y-y^3=\left(2x-y\right)^3\)
Bài 4 :
a, \(x^3+3x^2-x-3=x^2\left(x+3\right)-\left(x+3\right)=\left(x+1\right)\left(x-1\right)\left(x+3\right)\)
b, bạn xem lại đề nhé
c, \(x^2-4x+4-y^2=\left(x-2\right)^2-y^2=\left(x-2-y\right)\left(x-2+y\right)\)
d, \(5x+5-x^2+1=5\left(x+1\right)+\left(1-x\right)\left(x+1\right)=\left(x+1\right)\left(6-x\right)\)
\(a.=x\)
\(b.=y^3\)
\(c.=3xy\)
\(d.=-\frac{5}{2}a\)
\(e.=3yz\)
\(f.=-3xy\)
đề 1 bài 4
xét tam gics ABC và tam giác HBA có
góc B chung
góc BAC = góc BHA (=90 độ)
=> tam giác ABC đồng dạng vs tam giác HBA (g.g)
=> AB/HB=BC/AB=> AB^2=HB *BC
áp dụng đl py ta go trog tam giác vuông ABC có
BC^2 = AB^2 +AC^2=6^2+8^2=100
=> BC =\(\sqrt{100}\)=10 cm
ta có tam giác ABC đồng dạng vs tam giác HBA (cm câu a )
=> AC/AH=BC/BA=>AH=8*6/10=4.8CM
=>AB/BH=AC/AH=> BH=6*4.8/8=3,6cm
=>HC =BC-BH=10-3,6=6,4cm
dề 1 bài 1
5x+12=3x -14
<=>5x-3x=-14-12
<=>2x=-26
<=> x=-12
vạy S={-12}
(4x-2)*(3x+4)=0
<=>4x-2=0<=>x=1/2
<=>3x+4=0<=>x=-4/3
vậy S={1/2;-4/3}
đkxđ : x\(\ne2;x\ne-3\)
\(\dfrac{4}{x-2}+\dfrac{1}{x+3}=0\)
<=> 4(x+3)/(x-2)(x+3)+1(x-2)/(x-2)(x+3)
=> 4x+12+x-2=0
<=>5x=-10
<=>x=-2 (nhận)
vậy S={-2}
1A
\(a,\left(2x+3\right)^2=4x^2+12x+9\)
\(b,\left(6-3n\right)^2=36-36n+9n^2\)
\(c,\left(y-4\right)\left(y+4\right)=y^2-16\)
\(d,\left(\frac{a}{2}-4\right)^2=\frac{a^2}{4}-4a+16\)
1B
\(a,\left(x-\frac{3}{4}\right)^2=x^2-\frac{3}{2}x+\frac{9}{16}\)
\(b,\left(3t+1\right)^2=9t^2+6t+1\)
\(c,\left(3a+\frac{1}{3}\right)\left(\frac{1}{3}-3a\right)=\frac{1}{9}-9a^2\)
\(d,\left(a^2-2\right)^2=a^4-4a^2+4\)
2A
\(a,\left(\frac{a}{3}+4y\right)^2=\frac{a^2}{9}+\frac{8a}{3}y+16y^2\)
\(b,\left(\frac{1}{x}-\frac{3}{y}\right)^2=\frac{1}{x^2}-\frac{6}{xy}+\frac{9}{y^2}\)
\(c,\left(\frac{x}{2}-\frac{yz}{6}\right)\left(\frac{x}{2}+\frac{yz}{6}\right)=\frac{x^2}{4}-\frac{y^2x^2}{36}\)
\(d,\left(x^2+\frac{2}{5}y\right)\left(x^2-\frac{2}{5}y\right)=x^4-\frac{4}{25}y^2\)
2B
\(a,\left(y-2xy\right)^2=y^2-4xy^2+4x^2y^2\)
\(b,16\left(-\frac{1}{4}x+\frac{3}{5}y\right)^2=16\left(\frac{9}{25}y^2-\frac{3}{10}xy+\frac{1}{16}x^2\right)=\frac{144}{25}y^2-\frac{48}{10}xy+x^2\)
\(c,\left(-\frac{1}{3}ab^2+c^3\right)\left(-\frac{1}{3}ab^2-c^3\right)=\frac{1}{9}a^2b^4-c^6\)
\(d,\left(a+\frac{2}{3}\right)^2\left(a-\frac{2}{3}\right)^2=\left(a^2-\frac{4}{9}\right)^2=a^4-\frac{8}{9}a+\frac{16}{81}\)