a) 10 250                                 

b) 301

a) (5 + x)(x - 5) - x(x + 5) = 10

x² - 25 - x² - 5x = 10

-5x = 10 + 25

-5x = 35

x = 35 : (-5)

x = -7

b) x.(2x + 3) - 2(x² + x) = 2

2x² + 3x - 2x² - 2x = 2

x = 2

a: \(\left(x+5\right)\left(x-5\right)-x\left(x+5\right)=10\)

=>\(x^2-25-x^2-5x=10\)

=>-5x-25=10

=>-5x=35

=>x=-7

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

=>\(2x^2+3x-2x^2-2x=2\)

=>x=2

a) x = 5/8 : 3/4

x = 5/6

b) x = 5/6 - 1/12

x = 3/4

a)x=\(\dfrac{5}{8}:\dfrac{3}{4}=\dfrac{5}{6}\)

b) x=\(\dfrac{5}{6}-\dfrac{1}{12}=\dfrac{3}{4}\)

a \(x=\dfrac{5}{8}:\dfrac{3}{4}\)

\(x=\dfrac{5}{8}\times\dfrac{4}{3}\)

\(x=\dfrac{5}{6}\)

b \(x=\dfrac{5}{6}-\dfrac{1}{12}\)

\(x=\dfrac{10}{12}-\dfrac{1}{12}\)

\(x=\dfrac{9}{12}\)

\(x=\dfrac{3}{4}\)

a. `4x^2-20x+25=0`

`<=>(2x)^2-2.2x.5 +5^2=0`

`<=>(2x-5)^2=0`

`<=>2x-5=0`

`<=>x=5/2`

b. `(x-5)(x+5)-(x-3)^2=2(x-7)`

`<=>x^2-25-x^2+6x-9=2x-14`

`<=>6x-34=2x-14`

`<=>4x=20`

`<=>x=5`

\(a,4x^2-20x+25=0\Leftrightarrow\left(2x\right)^2-2.2x.5+5^2=0\)

\(\Leftrightarrow\left(2x-5\right)^2=0\Leftrightarrow x=\dfrac{5}{2}\)

b, \(\left(x-5\right)\left(x+5\right)-\left(x-3\right)^2=2\left(x-7\right)\)

\(\Leftrightarrow x^2-25-x^2+6x-9=2x-14\Leftrightarrow4x=20\Leftrightarrow x=5\)

a) Có: (2x)² - 2.2.5.x + 5² = 0

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

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

b) Có: x² - 25 - x² + 6x - 9 = 2x - 14

           ⇒ 6x - 36 = 2x - 14

           ⇒ 4x = 22

           ⇒ x = \(\dfrac{11}{2}\)

a: 5x=9,5

nên x=1,9

b: 42x=15,12

nên x=15,12:42=0,36

a, \(x=\dfrac{9,5}{5}=\dfrac{19}{10}\)

b, \(x=\dfrac{15,12}{42}=\dfrac{9}{25}\)

a.\(x\times5=9,5\)

\(\Rightarrow x=9,5:5=1,9\)

b.\(42\times x=15,12\)

\(\Rightarrow x=15,12:42=0,36\)

a: x=12

b: x=-19

c)x=-25

d)x=30

x=1/6

x=1/4

a) x = 1/6

b) x = 1/4

HT

a) 2/3 + x = 5/6

X = 5/6 - 2/3

X = 1/6

b)  x : 5/6 = 3/10

X = 5/6 x 3/10

X = 17/15

a) (x + 3)^2 - 4x - 12 = 0

<=> (x + 3)^2 - 4(x + 3) = 0

<=> (x + 3)(x - 1) = 0

<=> x = -3 hoặc x = 1

b) x(x + 5)(x- 5) - (x - 3)(x^2 + 3x + 9) = 7

<=> x^3 - 25x - x^3 + 27 = 7

<=> -25x + 27 = 7

<=> x = 4/5

a/ \(\left(x+3\right)^2-4x-12=0\)

\(\left(x+3\right)^2-4\left(x+3\right)=0\)

\(\left(x+3\right)\left(x+3-4\right)=0\)

\(\left[{}\begin{matrix}x+3=0\Rightarrow x=-3\\x+3-4=0\Rightarrow x=1\end{matrix}\right.\)

---

b/ \(x\left(x+5\right)\left(x-5\right)-\left(x-3\right)\left(x^2+3x+9\right)=7\)

\(x\left(x^2-25\right)-\left(x^3-27\right)=7\)

\(x^3-25x-x^3+27=7\)

\(-25x=-20\)

\(x=\dfrac{20}{25}=\dfrac{4}{5}\)

a, <=>x² +6x+9-4x-12=0

<=> x² +2x -3=0

<=> x² +3x -x-3=0

<=> x.(x+3) - (x+3) =0

<=> (x-1)(x+3)=0

<=> x=1 hoặc x=-3

b, <=> x(x² -25) - (x-3)(x+3)² -7=0 

<=> x³ -25x + (9-x²) (x+3) -7=0

<=> x³ -25x+ 9x+27-x³ -3x² -7=0

<=> -3x² -16x +20=0

<=>(3x-10)(x-2) =0 (đoạn này tự phân tích nha ^ ^)

<=> x= 10/3 hoặc x=2

Chúc bạn học tốt nha!

\(a,\Rightarrow x^2+4x+25-x^2=3\\ \Rightarrow4x=-22\Rightarrow x=-\dfrac{11}{2}\\ b,\Rightarrow\left(2x-3-4x-3\right)\left(2x-3+4x+3\right)=0\\ \Rightarrow6x\left(-2x-6\right)=0\Rightarrow\left[{}\begin{matrix}x=-3\\x=0\end{matrix}\right.\)