Question

Answer 1

Bài 5:

c: Ta có: \(7x\left(x-2\right)-5\left(x-1\right)=7x^2+3\)

\(\Leftrightarrow7x^2-14x-5x+5=7x^2+3\)

\(\Leftrightarrow-19x=-2\)

hay \(x=\dfrac{2}{19}\)

d: Ta có: \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)

\(\Leftrightarrow10x-16-12x+15=12x-16+11\)

\(\Leftrightarrow-14x=-4\)

hay \(x=\dfrac{2}{7}\)

Answer 2

Bài 6: 

a: Ta có: \(a\left(b-c\right)-b\left(a+c\right)+c\left(a-b\right)\)

\(=ab-ac-ab-bc+ac-bc\)

=-2bc

b: Ta có: \(a\left(1-b\right)+a\left(a^2-1\right)\)

\(=a\left(1-b+a^2-1\right)\)

\(=a\left(a^2-b\right)\)