giúp e bài 6,7,8,9,10 ạ
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6) \(=3\left(x-y\right)\left(1-2a\right)\)
7) \(=\left(x+2\right)\left(5+8y\right)\)
8) \(=3x\left(x-1\right)+6y\left(x-1\right)=3\left(x-1\right)\left(x+2y\right)\)
9) \(=2\left(2x-1\right)\left(2x+3\right)\)
10) \(=3x\left(x+3\right)\left(x-2\right)\)
1. 4x2 - 4x
= 4x(x - 1)
2. 3ax + 12x - 9
= 3(ax + 4x - 3)
3. 6xy + 2xy2 - 8x2
= 2x(3y + y2 - 4x)
4. -4ay + 10a - 8a2y
= -2a(2y - 5 + 8ay)
5. 10x3 - 8ax2
= 2x2(5x - 4a)
6. 3(x - y) - 6a(x - y)
= (3 - 6a)(x - y)
= 3(1 - 2a)(x - y)
7. 5(x + 2) + 8y(x + 2)
= (5 + 8y)(x + 2)
8. 3x(x - 1) - 6y(1 - x)
= 3x(x - 1) + 6y(x - 1)
= (3x + 6y)(x - 1)
= 3(x + 2y)(x - 1)
9. 4x(2x - 1) + 6(2x - 1)
= (4x + 6)(2x - 1)
= 2(2x + 3)(2x - 1)
10. 3x2(x + 3) - 6x(3 + x)
= 3x2(x + 3) - 6x(x + 3)
= (3x2 - 6x)(x + 3)
= 3x(x - 2)(x + 3)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 9:
6: \(\Leftrightarrow x+\dfrac{4}{3}-\dfrac{12}{5}=\dfrac{5}{2}-\dfrac{1}{4}+\dfrac{7}{8}=\dfrac{20-2+7}{8}=\dfrac{25}{8}\)
=>x=25/8-4/3+12/5=503/120
7: \(\Leftrightarrow\dfrac{1}{7}-\dfrac{1}{5}+x-\dfrac{3}{2}=\dfrac{16}{70}-\dfrac{9}{70}=\dfrac{1}{10}\)
=>x=1/10-1/7+1/5+3/2=58/35
8: \(\Leftrightarrow\dfrac{5}{4}-x+\dfrac{1}{5}-\dfrac{19}{20}=1-\dfrac{1}{2}+\dfrac{7}{10}=\dfrac{6}{5}\)
=>1/2-x=6/5
=>x=1/2-6/5=-7/10
9: \(\Leftrightarrow5-\dfrac{1}{3}+\dfrac{17}{4}-x=1+\dfrac{2-11}{12}=1-\dfrac{9}{12}=\dfrac{1}{4}\)
=>x=14/3+4=26/3
10: \(\Leftrightarrow\dfrac{-1}{12}+x-\dfrac{5}{12}=3-\dfrac{7}{6}+\dfrac{1}{2}\)
=>x-1/2=11/6+1/2
=>x=11/6+1=17/6
\(#nKaizz\)
`9,`
`6, 1 1/3 - 2 2/5 + x= 5/2 - (1/4 - 7/8)`
`4/3 -12/5 + x = 5/2 - (-5/8)`
`4/3 - 12/5 + x=25/8`
`-16/15 + x=25/8`
`x=25/8 - (-16/15)`
`x=25/8 + 16/15 = 503/120`
`7, 1/7 - (1/5 - x + 1 1/2)= 8/35 - 9/70`
`1/7 - (1/5 - x + 3/2)= 1/10`
`1/5 - x + 3/2 = 1/7 -1/10`
`1/5 -x + 3/2 = 3/70`
`1/5 -x=3/70 - 3/2`
`1/5-x=-51/35`
`x=1/5 - (-51/35)`
`x=1/5 + 51/35 = 58/35`
`8, 5/4 - x +(1/5 - 19/20)= 1- (1/2 - 7/10)`
`5/4 - x+ -3/4 = 1- (-1/5)`
`5/4 - x+ -3/4 = 6/5`
`5/4 - x=6/5 - (-3/4)`
`5/4 - x=39/20`
`x=5/4 - 39/20`
`x=-7/10`
`9, 5- (1/3 - 4 1/4+x) = 1+ (1/6 - 11/12)`
`5- (1/3- 4 1/4+x)=1+ -3/4 `
`5- (1/3 - 4 1/4+x) = 1/4`
`1/3- 4 1/4 +x=5-1/4`
`-47/12 +x=19/4`
`x=19/4 - (-47/12)`
`x=26/3`
`10, 1/4 - (1/3-x+5/12)=3-(1 1/6 - 1/2)`
`1/4-(1/3-x+5/12)=3-2/3`
`1/4 - (1/3-x+5/12) =7/3`
`1/3 - x+5/12 = 1/4 - 7/3`
`1/3-x+5/12 = -25/12`
`1/3-x = (-25/12)-5/12`
`1/3-x = -5/2`
`x=1/3 - (-5/2)`
`x=17/6`
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 2:
a: Ta có: ΔABC cân tại A
mà AH là đường cao
nên AH là tia phân giác của góc BAC
b: Xét ΔAMH vuông tại M và ΔANH vuông tại N có
AH chung
\(\widehat{MAH}=\widehat{NAH}\)
Do đó: ΔAMH=ΔANH
Suy ra: AM=AN
hay ΔAMN cân tại A
c: Xét ΔABC có AM/AB=AN/AC
nên MN//BC
d: \(AH^2-AN^2=HN^2\)
\(BH^2-BM^2=MH^2\)
mà HN=MH
nên \(AH^2-AN^2=BH^2-BM^2\)
hay \(AH^2+BM^2=BH^2+AN^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 2: Chọn C
Bài 4:
a: \(\widehat{C}=180^0-80^0-50^0=50^0\)
Xét ΔABC có \(\widehat{A}=\widehat{C}< \widehat{B}\)
nên BC=AB<AC
b: Xét ΔABC có AB<BC<AC
nên \(\widehat{C}< \widehat{A}< \widehat{B}\)