Question

BT3/6. Tìm x, biết

a/ 2x(12x-5)-8x(3x-1)=30

b/3x(3-2x)+6x(x-1)=15

Answer 1

Câu a : \(2x\left(12x-5\right)-8x\left(3x-1\right)=30\)

\(\Leftrightarrow24x^2-10x-24x^2+8x=30\)

\(\Leftrightarrow-2x=30\)

\(\Leftrightarrow x=-15\)

Vậy \(x=-15\)

Câu b : \(3x\left(3-2x\right)+6x\left(x-1\right)=15\)

\(\Leftrightarrow9x-6x^2+6x^2-6x=15\)

\(\Leftrightarrow3x=15\)

\(\Leftrightarrow x=5\)

Vậy \(x=5\)

Answer 2

a, 2x(12x−5)−8x(3x−1)=302x(12x−5)−8x(3x−1)=30

24x2−10x−24x2+8x=3024x2−10x−24x2+8x=30

(24x2−24x2)−(10x−8x)=24(24x2−24x2)−(10x−8x)=24

−2x=24−2x=24

x=−12

Answer 3

b, 3x(3−2x)+6x(x−1)=153x(3−2x)+6x(x−1)=15

9x−6x2+6x2−6x=159x−6x2+6x2−6x=15

(9x−6x)+(−6x2+6x2)=15(9x−6x)+(−6x2+6x2)=15

3x=153x=15

x=5