Trả lời:

\(3x+1+5\times3x+2=144\)

\(\Leftrightarrow3x+1+15x+2=144\)

\(\Leftrightarrow18x=141\)

\(\Leftrightarrow x=\frac{47}{8}\)

Vậy \(x=\frac{47}{8}\)

\(B=5\cdot\left(2x-1\right)^2+4\cdot\left(x-1\right)\cdot\left(x+3\right)-2\cdot\left(5\cdot3x\right)\)

\(=5\left(4x^2-4x+1\right)+\left(4x-4\right)\cdot\left(x+3\right)-2\cdot15x\)

\(=20x^2-20x+5+4x^2+12x-4x-12-2\cdot15x\)

\(=20x^2-20x+5+4x^2+12x-4x+12-30x\)

\(=24x^2-42x-7\)

(B=5left(2x-1 ight)^2+4left(x-1 ight)left(x+3 ight)-2left(5.3x ight)=5left(4x^2-4x+1 ight)+4left(x^2-4x+3 ight)-30x=20x^2-20x+5+4x^2-16x+12-30x=24x^2-66x+17)

\(B=5.\left(2x-1\right)^2+4\left(x-1\right)\left(x+3\right)-2\left(5.3x\right)\)

\(B=5\left(4x^2-4x-1\right)+4\left(x^2+3x-x-3\right)-30x\)

\(B=20x^2-20x-5+4x^2+8x-12-30x\)

\(B=24x^2-2x-17\)

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dễ tích mình rồi mình giải cho

1) \(-\frac{2}{3}\left(x-\frac{1}{4}\right)=\frac{1}{3}\left(2x-1\right)\)

\(-\frac{2}{3}x+\frac{1}{6}=\frac{2}{3}x-\frac{1}{3}\)

\(-\frac{2}{3}x-\frac{2}{3}x=-\frac{1}{3}-\frac{1}{6}\)

\(-\frac{4}{3}x=-\frac{1}{2}\)

\(x=\left(-\frac{1}{2}\right):\left(-\frac{4}{3}\right)\)

\(x=\frac{3}{8}\)

a) x = 12  

b) x= 27              

c) x = 3 

d) x = 2

a) 71 - (33 + x) = 26
             33 + x  = 71 - 26
             33 + x  = 45
                     x  = 45 - 33
                     x  =     12