Giải giúp bài 1 2 3 4 của bài 15 i
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10/11+9/10 = 199/110
15/30+7/30 = 11/15
1/2+1/3 = 5/6
3/5+11/15 = 4/3
3/4+1/6 = 11/12
5/11+4/11 = 9/11
BẠN THẬT XUẤT SẮC
CẢM ƠN BẠN NHA
CHÚC BAN CUỐI TUẦN VUI VẺ
`5)(6-sqrt6)/(1-sqrt6)+(6-sqrt6)/sqrt6=(sqrt6(sqrt6-1))/(1-sqrt6)+(sqrt6(sqrt6-1))/sqrt6=-sqrt6+sqrt6-1=-1` $\\$ `6)1/(sqrt2-sqrt3)-1/(sqrt3+sqrt2)=(sqrt2+sqrt3)/(2-3)-(sqrt3-sqrt2)/(3-2)=-(sqrt2+sqrt3)-sqrt3+sqrt2=-2sqrt3` $\\$ `7)1/(sqrt5+sqrt3)-1/(sqrt5-sqrt3)=(sqrt5-sqrt3)/(5-3)-(sqrt5+sqrt3)/(5-3)=(sqrt5-sqrt3-sqrt5-sqrt3)/2=-sqrt3` $\\$ `8)6/(1-sqrt3)-(3sqrt3-3)/(sqrt3+1)=(6(1+sqrt3))/(1-3)-(3(sqrt3-1)^2)/(3-1)=(-6(sqrt3+1)-3(4-2sqrt3))/2=-9`
Bài 3:
15:40=37,5%
Bài 4:
=250x10%=25
Bài 5:
Số cần tìm là:
75:25%=300
`15)(-5sqrtx+4)/(3sqrtx-2)+(6sqrtx+4)/(2sqrtx+3)+(29sqrtx-28)/(3(6x+5sqrtx-6))`
`=(3(-5sqrtx+4)(2sqrtx+3)+3(6sqrtx+4)(3sqrtx-2)+29sqrtx-28)/(3(3sqrtx-2)(2sqrtx+3))`
`=(-30x-21sqrtx+36+54x-24+29sqrtx-28)/(3(3sqrtx-2)(2sqrtx+3))`
`=(24x+8sqrtx-16)/(3(3sqrtx-2)(2sqrtx+3))`
`=(8(3sqrtx-2)(sqrtx+1))/(3(3sqrtx-2)(2sqrtx+3))`
`=(8(sqrtx+1))/(3(2sqrtx+3))`
14, \(\frac{-7\sqrt{x}+7}{5\sqrt{x}-1}+\frac{2\sqrt{x}-2}{\sqrt{x}+2}+\frac{39\sqrt{x}+12}{5x+9\sqrt{x}-2}\)
\(=\frac{-7\sqrt{x}+7}{5\sqrt{x}-1}+\frac{2\sqrt{x}-2}{\sqrt{x}+2}+\frac{39\sqrt{x}+12}{\left(\sqrt{x}+2\right)\left(5\sqrt{x}-1\right)}\)
\(=\frac{\left(-7\sqrt{x}+7\right)\left(\sqrt{x}+2\right)+\left(2\sqrt{x}-2\right)\left(5\sqrt{x}-1\right)+39\sqrt{x}+12}{\left(5\sqrt{x}-1\right)\left(\sqrt{x}+2\right)}\)
\(=\frac{-7x-14\sqrt{x}+7\sqrt{x}+14+10x-2\sqrt{x}-10\sqrt{x}+2+39\sqrt{x}+12}{\left(5\sqrt{x}-1\right)\left(\sqrt{x}+2\right)}\)
\(=\frac{3x+20\sqrt{x}+28}{\left(5\sqrt{x}-1\right)\left(\sqrt{x}+2\right)}\)
\(=\frac{\left(3\sqrt{x}+14\right)\left(\sqrt{x}+2\right)}{\left(5\sqrt{x}-1\right)\left(\sqrt{x}+2\right)}\)
\(=\frac{3\sqrt{x}+14}{5\sqrt{x}-1}\)
Dễ mak
nhưng mik nhìn đề thấy dài quá nên ko muốn làm
hihi^_$
\(=\left(2x+\frac{3}{4}\right)\frac{7}{9}=\frac{15}{8}\)
\(=2x+\frac{3}{4}\)\(=\frac{15}{8}:\frac{7}{9}\)
=\(2x+\frac{3}{4}=\frac{135}{56}\)
=2x=\(\frac{135}{56}-\frac{3}{4}\)
=2x=\(\frac{93}{56}\)
x=\(\frac{93}{56}:2\)
x=\(\frac{93}{112}\)
k nha
`1)1/(1-sqrt2)-1/(1+sqrt2)=(1+sqrt2)/(1-2)-(sqrt2-1)/(2-1)=-(1+sqrt2)-sqrt2+1=-2sqrt2` $\\$ `2)1/(1+sqrt5)+1/(sqrt5-1)=(sqrt5-1)/(5-1)+(sqrt5+1)/(5-1)=(sqrt5-1+sqrt5+1)/4=sqrt5/2` $\\$ `3)4/(1-sqrt3)+(sqrt3-1)/(sqrt3+1)=(4(sqrt3+1))/(1-3)+(sqrt3-1)^2/(3-1)=(-4(sqrt3+1)+4-2sqrt3)/2=-3sqrt3` $\\$ `4)(2-sqrt5)/(2+sqrt5)+(sqrt5+2)/(sqrt5-2)=(2-sqrt5)^2/(4-5)+(sqrt5+2)^2/(5-4)=-(2-sqrt5)^2+(sqrt5+2)^2=9+4sqrt5-9+4sqrt5=8sqrt5`
18) Ta có: \(\dfrac{2-\sqrt{2}}{1-\sqrt{2}}+\dfrac{\sqrt{2}-\sqrt{6}}{\sqrt{3}-1}\)
\(=\dfrac{-\sqrt{2}\left(1-\sqrt{2}\right)}{1-\sqrt{2}}+\dfrac{\sqrt{2}\left(1-\sqrt{3}\right)}{-\left(1-\sqrt{3}\right)}\)
\(=-2\sqrt{2}\)