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14 tháng 8 2019

a)262-242=(26-24)(26+24)=2.50=100

272-252=(27-25)(27+25)=2.52=104

mà 100<104 => 262-242<272-252

14 tháng 8 2019

\(hdt:\left(a-b\right)\left(a+b\right)=a^2-b^2\)

\(3C=3\left(4+1\right)\left(4^2+1\right)\left(4^4+1\right)\left(4^8+1\right)\left(4^{16}+1\right)\)

\(3C=\left(4-1\right)\left(4+1\right)\left(4^2+1\right)\left(4^4+1\right)\left(4^8+1\right)\left(4^{16}+1\right)\)

\(3C=\left(4^2-1\right)\left(4^2+1\right)\left(4^4+1\right)\left(4^8+1\right)\left(4^{16}+1\right)\)

\(3C=\left(4^4-1\right)\left(4^4+1\right)\left(4^8+1\right)\left(4^{16}+1\right)\)

\(3C=\left(4^8-1\right)\left(4^8+1\right)\left(4^{16}+1\right)\)

\(3C=\left(4^{16}-1\right)\left(4^{16}+1\right)=4^{32}-1\Rightarrow3C< D\Rightarrow C< D\)

13 tháng 8 2019

a)\(A=26^2-24^2=\left(26-24\right)\left(26+24\right)=2.50\)

\(B=27^2-25^2=\left(27-25\right)\left(27+25\right)=2.52\)

Vì 52 > 50 nên B > A

13 tháng 11 2023

Bài 1:

\(A=26^2-24^2=\left(26-24\right)\left(26+24\right)=2\cdot50=100\)

\(B=27^2-25^2=\left(27-25\right)\left(27+25\right)=2\cdot52=104\)

=>A<B

Bài 2:

\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)

=>\(4\left(x^2+2x+1\right)+4x^2-4x+1-8\left(x^2-1\right)=11\)

=>\(4x^2+8x+4+4x^2-4x+1-8x^2+8=11\)

=>4x+13=11

=>4x=-2

=>\(x=-\dfrac{1}{2}\)

9 tháng 7 2023

a) 25x² - 16

= (5x)² - 4²

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

b) 16a² - 9b²

= (4a)² - (3b)²

= (4a - 3b)(4a + 3b)

c) 8x³ + 1

= (2x)³ + 1³

= (2x + 1)(4x² - 2x + 1)

d) 125x³ + 27y³

= (5x)³ + (3y)³

= (5x + 3y)(25x² - 15xy + 9y²)

e) 8x³ - 125

= (2x)³ - 5³

= (2x - 5)(4x² + 10x + 25)

g) 27x³ - y³

= (3x)³ - y³

= (3x - y)(9x² + 3xy + y²)

9 tháng 7 2023

a) \(25x^2-16=\left(5x-4\right)\left(5x+4\right)\)

b) \(16a^2-9b^2=\left(4a-3b\right)\left(4a+3b\right)\)

c) \(8x^3+1=\left(2x+1\right)\left(4x^2-2x+1\right)\)

d) \(125x^3+27y^3=\left(5x+3y\right)\left(25x^2-15xy+9y^2\right)\)

e) \(8x^3-125=\left(2x-5\right)\left(4x^2-10x+25\right)\)

g) \(27x^3-y^3=\left(3x-y\right)\left(9x^2+3xy+y^2\right)\)

Ta có: \(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

\(=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

\(=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)

\(=\left(2^{16}-1\right)\left(2^{16}+1\right)\)

\(=2^{32}-1< 2^{32}\)

\(\Leftrightarrow A< B\)

9 tháng 7 2023

a) 25x² - 10xy + y²

= (5x)² - 2.5x.y + y²

= (5x - y)²

b) 4/9 x² + 20/3 xy + + 25y²

= (2/3 x)² + 2.2/3 x.5y + (5y)²

= (2/3 x + 5y)²

c) 9x² - 12x + 4

= (3x)² - 2.3x.2 + 2²

= (3x - 2)²

d) Sửa đề: 16u²v⁴ - 8uv² + 1

= (4uv²)² - 2.4uv².1 + 1²

= (4uv² - 1)²

chỉ cần giải mỗi c và d thui

 

B=24(5^2+1)(5^4+1)(5^8+1)(5^16+1)
=(5^2-1)(5^2+1)(5^4+1)(5^8+1)(5^16+1)
=(5^4-1)(5^4+1)(5^8+1)(5^16+1)
=(5^8-1)(5^8+1)(5^16+1)
=(5^16-1)(5^16+1)
=5^32-1

Vậy B<A