Lời giải:

a.

PT $\Leftrightarrow 3x^2+\frac{x}{2}-3x^2+3x+2=0$
$\Leftrightarrow \frac{7}{2}x+2=0$
$\Leftrightarrow \frac{7}{2}x=-2$
$\Leftrightarrow x=-2: \frac{7}{2}=\frac{-4}{7}$
b.

PT $\Leftrightarrow 5x^2-3-5x^2-6x=0$

$\Leftrightarrow -3-6x=0$

$\Leftrightarrow 6x=-3$

$\Leftrightarrow x=\frac{-3}{6}=\frac{-1}{2}$

Bạn xem đã viết đúng đề chưa vậy?

a: Sửa đề: \(\left(6x^3+x^2\right):2x-3x+2=0\)

ĐKXĐ: x<>0

Ta có: \(\left(6x^3+x^2\right):2x-3x+2=0\)

=>\(\frac{6x^3}{2x}+\frac{x^2}{2x}-3x+2=0\)

=>\(3x+\frac12x-3x+2=0\)

=>\(\frac12x+2=0\)

=>\(\frac12x=-2\)

=>x=-4(nhận)

b: Sửa đề: \(\left(5x^4-3x^2\right):x^2-x\left(5x+6\right)=0\)

ĐKxĐ: x<>0

Ta có: \(\left(5x^4-3x^2\right):x^2-x\left(5x+6\right)=0\)

=>\(5x^2-3-5x^2-6x=0\)

=>-6x-3=0

=>6x+3=0

=>3(2x+1)=0

=>2x+1=0

=>2x=-1

=>\(x=-\frac12\) (nhận)

\(3x^2-5x-8=3x\left(x+1\right)-8\left(x+1\right)=\left(x+1\right)\left(3x-8\right)\)

Lời giải:

$5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2$

$5^x(1+5+5^2+5^3)=88.89:2-16$

$5^x.156=3900$

$5^x=3900:156=25=5^2$

$\Rightarrow x=2$

a)=\(3x^3-15x^2+21x\)

b)\(=-2x^4y-10x^2y+2xy\)

c)\(=-x^3+6x^2+5x-4x^2+24x+20=-x^3+2x^2+29x+20\)

d)\(=2x^4-3x^3+4x^2-2x^2+3x-4=2x^4-3x^32x^2+3x-4\)

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

f)\(=-2x^2y^3+y-3\)

g)\(=3xy^4-\dfrac{1}{2}y^2+2x^2y\)

h)\(=9x^2-6x+1-7x^2-14=2x^2-6x-13\)

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

j)\(=\left(x+2y\right)\left(x^2-2y+4y^2\right):\left(x+2y\right)=x^2-2y+4y^2\)

Bài 2:

a: =>2x^2-4x+1=x^2+x+5

=>x^2-5x-4=0

=>\(x=\dfrac{5\pm\sqrt{41}}{2}\)

b: =>11x^2-14x-12=3x^2+4x-7

=>8x^2-18x-5=0

=>x=5/2 hoặc x=-1/4

1) 2x – (3 – 5x) = 4( x +3)

<=>2x-3+5x=4x+12

<=>2x-3+5x-4x-12=0

<=>3x-15=0

<=>x=5

2) 5(2x-3) - 4(5x-7) =19 - 2(x+11)

<=>10x-15-20x+28=19-2x-22

<=>10x-15-20x+28-19+2x+22=0

<=>-8x+16=0

<=>x=2

tham khảo

1) 2x – (3 – 5x) = 4( x +3)

<=>2x-3+5x=4x+12

<=>2x-3+5x-4x-12=0

<=>3x-15=0

<=>x=5

2) 5(2x-3) - 4(5x-7) =19 - 2(x+11)

<=>10x-15-20x+28=19-2x-22

<=>10x-15-20x+28-19+2x+22=0

<=>-8x+16=0

<=>x=2