Question

tìm x

a,2x^2-6x=0

b,(x-1)^2+4(4-x)=0

c,2-25x^2=0

 

rút gọn

(5x+3)^2-2(x+3)(5x+3)+(x+3)

Answer 1

a)2x²-6x=0

=>x(2x-6)=0

=>x=0 hoặc 2x-6=0

Với 2x-6=0 =>2x=6 <=>x=3

 

Answer 2

đề b sai tổ mẹ r`

Answer 3

c,2-25x²=0

\(\Rightarrow x^2=\frac{2}{25}\)

\(\Rightarrow x=\pm\frac{\sqrt{2}}{\sqrt{25}}=\pm\frac{\sqrt{2}}{5}\)

Bài 2: 

(5x+3)^2-2(x+3)(5x+3)+(x+3)

=25x²+30x+9-10x²-36x-18+x+3

=15x²-5x-6