a: Ta có: \(\left(x+2\right)^2+\left(2x-1\right)^2-\left(x-3\right)^2=36\)

\(\Leftrightarrow x^2+4x+4+4x^2-4x+1-x^2+6x-9=36\)

\(\Leftrightarrow4x^2+6x-4-36=0\)

\(\Leftrightarrow4x^2+6x-40=0\)

\(\text{Δ}=6^2-4\cdot4\cdot\left(-40\right)=676\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{-6-26}{8}=-4\\x_2=\dfrac{-6+26}{8}=\dfrac{5}{2}\end{matrix}\right.\)

a: x/147=5/7

=>x=147*5/7=105

b: x-2/36=7/12

=>x-2/36=21/36

=>x=21/36+2/36=23/36

7 x 8 = 56       16 : 2 = 8       36 : 6 = 6       49 : 7 = 7

2 x 5 = 10       72 : 8 = 9       9 x 3 = 27       63 : 7 = 9

6 x 4 = 24       25 : 5 = 5       4 x 8 = 32       7 x 5 = 35

7 x 8 = 56

2 x 5 = 10

6 x 4 = 24

16 : 2 = 8 

72 : 8 = 9

25 : 5 = 5

36 : 6 = 6

9 x 3 = 27

4 x 8 = 32

49 : 7 = 7

63 : 7 = 9

7 x 5 = 35

=>x+2=-9

=>x=-11

\(=>\left(x+2\right).28=7.\left(-36\right)\\ =>\left(x+2\right).28=-252\\ =>x+2=-252:28\\ =>x+2=-9\\ =>x=-11\)

\(\Rightarrow28.\left(x+2\right)=-36.7\)

\(\Rightarrow28x+56+252=0\)

\(\Rightarrow28x=-308\)

\(\Rightarrow x=-11\)

b: 

ĐKXĐ: x>=4

\(5\sqrt{4x-16}-\dfrac{7}{3}\cdot\sqrt{9x-36}=36-3\sqrt{x-4}\)

=>\(5\cdot2\cdot\sqrt{x-4}-\dfrac{7}{3}\cdot3\cdot\sqrt{x-4}+3\sqrt{x-4}=36\)

=>\(6\sqrt{x-4}=36\)

=>\(\sqrt{x-4}=6\)

=>x-4=36

=>x=40

\(\dfrac{3}{8}x-\dfrac{1}{4}-\dfrac{2}{3}x+\dfrac{1}{9}=\dfrac{7}{36}\)

=> \(\dfrac{3}{8}x-\dfrac{2}{3}x-\left(\dfrac{1}{4}+\dfrac{1}{9}\right)=\dfrac{7}{36}\)

=> \(\dfrac{-7}{24}x-\dfrac{5}{36}=\dfrac{7}{36}\)

=> \(\dfrac{-7}{24}x=\dfrac{1}{3}\)

=> \(x=\dfrac{-8}{7}\)

(x - 7)² - (x + 4)(x - 4) = 36 - 2x

=> x² - 14x + 49 - (x² - 16) = 36 - 2x

=> x² - 14x + 49 -x² + 16 = 36 - 2x

=> -14x + 2x = -29

=> -12x = -29

=> x = 29/12

( x - 7 )² - ( x - 4 )( x + 4 ) = 36 - 2x

<=> x² - 14x + 49 - ( x² - 16 ) = 36 - 2x

<=> x² - 14x + 49 - x² + 16 = 36 - 2x

<=> 65 - 14x = 36 - 2x

<=> 65 - 36 = -2x + 14x

<=> 29 = 12x

<=> x = 29/12

\(\left(x-7\right)^2-\left(x+4\right)\left(x-4\right)=36-2x\)

\(\left(x^2-14x+49\right)-\left(x^2-16\right)=36-2x\)

\(x^2-14x+49-x^2+16=36-2x\)

\(14x+65=36-2x\)

\(14x-2x=36+65\)

\(12x=101\)

\(x=101:12\)

\(x\approx8\)