Question

a    9x²-18x=0

b    x(x-2)+5(2+x)=0

c    3x²-147=0

d    4x²-12x=0

e    320-5x²=0

f     2x(x-17)+(17-x)=0

Answer 1

\(2x\left(x-17\right)+\left(17-x\right)=0\)

\(\Leftrightarrow\left(2x-1\right)\left(x-17\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=17\end{cases}}\)

Answer 2

\(9x^2-18x=0\)

\(\Leftrightarrow9x\left(x-2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}\)

Answer 3

b) \(x\left(x-2\right)+5\left(2+x\right)=0\)

\(\Leftrightarrow x^2-2x+10+5x=0\)

\(\Leftrightarrow x^2+3x+10=0\)

Dễ thấy phương trình vô nghiệm do vế trái luôn dương

Answer 4

\(3x^2-147=0\)

\(\Leftrightarrow3\left(x^2-49\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)

Answer 5

d) \(4x^2-12x=0\)

\(\Leftrightarrow4x\left(x-3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}\)

Answer 6

e) \(320-5x^2=0\)

\(\Leftrightarrow5\left(72-x^2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=\sqrt{72}\\x=-\sqrt{72}\end{cases}}\)