1:

a: =12/10-7/10=5/10=1/2

b: \(=\dfrac{4}{13}-\dfrac{4}{13}+\dfrac{-5}{11}-\dfrac{6}{11}=-\dfrac{11}{11}=-1\)

2: 

a: x+2/7=-11/7

=>x=-11/7-2/7=-13/7

b: (x+3)/4=-7/2

=>x+3=-14

=>x=-17

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he he he he he he

bài 1:

bn lấy giá trị của √(4^2-3,9^2) là dc

bài 2

AB+BC=2√(3^2+4^2)=??

2^{x + 1} + 7. 2^{x + 3} = 232
2^x . 2 + 7. 2^x . 2³ = 232
2^x . 2 + 7 . 8 . 2^x = 232
2^x . 2 + 56 . 2^x = 232
2^x . ( 2 + 56 ) = 232
2^x . 58 = 232
2^x = 232 : 58
2^x = 4
2^x = 2²
=> x = 2

2^x x 2 + 7 x 2^x x 2³=232

2^x(2+7 x 2³)=232

2^x x 58 =232

2^x=232:58=4=2²

^=>x=2

Bài 5: 

a: BC=10cm

b: HA=4,8cm

HB=3,6(cm)

HC=6,4(cm)

Bài 6:

\(x^3=6+3\sqrt[3]{\left(3+2\sqrt{2}\right)\left(3-2\sqrt{2}\right)}\left(\sqrt[3]{3+2\sqrt{2}}+\sqrt[3]{3-2\sqrt{2}}\right)\\ \Leftrightarrow x^3=6+3x\sqrt[3]{1}\\ \Leftrightarrow x^3-3x=6\\ y^3=34+3\sqrt[3]{\left(17+12\sqrt{2}\right)\left(17-12\sqrt{2}\right)}\left(\sqrt[3]{17+12\sqrt{2}}+\sqrt[3]{17-12\sqrt{2}}\right)\\ \Leftrightarrow y^3=34+3y\sqrt[3]{1}\\ \Leftrightarrow y^3-3y=34\\ \Leftrightarrow P=x^3-3x+y^3-3y+1980=6+34+1980=2020\)

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