(2x-3)(x-3)(x+3)

=(2x-3)(x\(^2\)-9)

=2x\(^{^{ }3}\)-3x\(^2\)-18x+27

a, 4x\(^2\)-25-(2x-5)(2x+7)=0

=>(2x-5)(2x+5)-(2x-5)(2x+7)=0

=>(2x-5)(2x+5-2x-7)=0

=>(2x-5)(-2)=0

=>2x-5=0

=>2x=5

=>x=\(\dfrac{5}{2}\)

b,2x\(^3\)+3x\(^2\)+2x+3=0

=>2x(x\(^2\)+1)+3(x\(^2\)+1)=0

=>(x\(^2\)+1)(2x+3)=0

=>\(\left[{}\begin{matrix}x^2-1=0\\2x+3=0\end{matrix}\right.\)=>\(\left[{}\begin{matrix}x=\pm1\\x=\dfrac{-3}{2}\end{matrix}\right.\)

Choose the word whose underlined part is pronounced differently from the others

A. looked

B. laughed

C. moved

D. stepped

nam á

Đáy bé thửa ruộng đó là:

120:3x2=80 (m)

CHiều cao thửa ruộng đó là:    80-5=75(m)

Diện tích thửa ruộng đó là:
(80+120)x75:2=7500 (m2)

Số kg thóc thu hoạch được trên thửa ruộng đó là:

7500:100x64,5=4837,5 (kg thóc)

ta có (x+8)\(⋮\)(x\(^2\)+1)

=>(x+8)(x-8)\(⋮\)(x\(^2\)+1)

=>(x\(^2\)-64)\(⋮\)(x\(^2\)+1)

=>(x\(^2\)+1)+65\(⋮\)(x\(^2\)+1)

=>65\(⋮\)(x\(^2\)+1)

=>(x\(^2\)+1)\(\in\)U(65)

=>(x\(^2\)+1)\(\in\){\(\pm1;\pm65\)}

=>x\(^2\)\(\in\){0;64}

=>x\(\in\){0;\(\pm\)8}

a, x(x-2)-y(x-2)

=(x-2)(x-y)

b,x\(^2\)+4xy-16+4y\(^2\)

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

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