Bài 1 :

a ) Ta có :

\(\left(x+y\right)^2=x^2+y^2+2xy=20+16=36\)

b ) Ta có :

\(x^2+y^2=\left(x+y\right)^2-2xy=64-30=34\)

1: =(x+y-3x)(x+y+3x)

=(-2x+y)(4x+y)

2: =(3x-1-4)(3x-1+4)

=(3x+3)(3x-5)

=3(x+1)(3x-5)

3: =(2x)^2-(x^2+1)^2

=-[(x^2+1)^2-(2x)^2]

=-(x^2+1-2x)(x^2+1+2x)

=-(x-1)^2(x+1)^2

4: =(2x+1+x-1)(2x+1-x+1)

=3x(x+2)

5: =[(x+1)^2-(x-1)^2][(x+1)^2+(x-1)^2]

=(2x^2+2)*4x

=8x(x^2+1)

6: =(5x-5y)^2-(4x+4y)^2

=(5x-5y-4x-4y)(5x-5y+4x+4y)

=(x-9y)(9x-y)

7: =(x^2+xy+y^2+xy)(x^2+xy-y^2-xy)

=(x^2+2xy+y^2)(x^2-y^2)

=(x+y)^3*(x-y)

8: =(x^2+4y^2-20-4xy+16)(x^2+4y^2-20+4xy-16)

=[(x-2y)^2-4][(x+2y)^2-36]

=(x-2y-2)(x-2y+2)(x+2y-6)(x+2y+6)

a) M = (x² + 3xy - 3x³) + (2y³ - xy + 3x³)

= x² + 3xy - 3x³ + 2y³ - xy + 3x³

= x² + (3xy - xy) + (-3x³ + 3x³) + 2y³

= x² + 2xy + 2y³

Tại x = 5 và y = 4

M = 5² + 2.5.4 + 2.4³

= 25 + 40 + 2.64

= 65 + 128

= 193

b) N = x²(x + y) - y(x² - y²)

= x³ + x²y - x²y + y³

= x³ + (x²y - x²y) + y³

= x³ + y³

Tại x = -6 và y = 8

N = (-6)³ + 8³

= -216 + 512

= 296

c) P = x² + 1/2 x + 1/16

= (x + 1/2)²

Tại x = 3/4 ta có:

P = (3/4 + 1/2)² = (5/4)² = 25/16

1) a) 4⁸.2²⁰ = (2²)⁸.2²⁰

= 2¹⁶.2²⁰ = 2³⁶

-----------

9¹².27⁵.81³ = (3²)¹².(3³)⁵.(3⁴)⁴

= 3²⁴.3¹⁵.3¹⁶ = 3⁵⁵

--------

64³.4⁵.16² = (4³)³.4⁵.(4²)²

= 4⁹.4⁵.4⁴ = 4¹⁸

b) 25²⁰.125⁴ = (5²)²⁰.(5³)⁴

= 5⁴⁰.5¹² = 5⁵²

--------

x⁷.x³.x⁴ = x¹⁴

--------

3⁶.4⁶ = (3.4)⁶ = 12⁶

2) a) 2² = 4

2³ = 8

2⁴ = 16

2⁵ = 32

2⁶ = 64

2⁷ = 128

2⁸ = 256

2⁹ = 512

2¹⁰ = 1024

b) 3² = 9

3³ = 27

3⁴ = 81

3⁵ = 243

c) 4² = 16

4³ = 64

4⁴ = 256

d) 5² = 25

5³ = 125

5⁴ = 625

b: \(=\left(x^2+3x+1-3x+1\right)^2=\left(x^2+2\right)^2\)

Câu 1 :

a, 8.( -5 ).( -4 ).2

= [ 8.2 ].[( -5 ).(-4 ]

= 16.20

= 320

b, \(1\frac{3}{7}+\frac{-1}{3}+2\frac{4}{7}\)

\(=\frac{10}{7}+\frac{-1}{3}+\frac{18}{7}\)

\(=\frac{11}{3}\)

c, \(\frac{8}{5}.\frac{2}{3}+\frac{-5.5}{3.5}\)

\(=\frac{8}{3}+\frac{-5}{3}\)

\(=\frac{3}{3}=1\)

d, \(\frac{6}{7}+\frac{5}{8}:5-\frac{3}{16}.\left(-2\right)^2\)

\(=\frac{6}{7}+\frac{1}{8}-\frac{3}{16}.4\)

\(=\frac{55}{56}-\frac{3}{4}\)

\(=\frac{13}{56}\)

Câu 2 :

a, 2x + 10 = 16

    2x = 16 + 10

    2x = 26

    x = 26 : 2

    x = 13

b, \(x-\frac{1}{3}=\frac{5}{4}\)

\(x=\frac{5}{4}+\frac{1}{3}\)

\(x=\frac{19}{12}\)

c, \(2x+3\frac{1}{3}=7\frac{1}{3}\)

\(2x+\frac{10}{3}=\frac{22}{3}\)

\(2x=\frac{22}{3}-\frac{10}{3}\)

\(2x=4\)

\(x=4:2\)

\(x=2\)

d, \(\left(\frac{2}{11}+\frac{1}{3}\right)x=\left(\frac{1}{7}-\frac{1}{8}\right).56\)

\(\frac{17}{33}x=1\)

\(x=1-\frac{17}{33}\)

\(x=\frac{16}{33}\)

đề dài thế bạn sao làm nổi???????????

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