Question

bài 1: Giải phương trình a. ( 5-x)(2+3x) = 4-9x² b. 25-x² = 4x(5+x) c. x²-2x+1 = 3x(x-1) d. 4(7x-3) = 7x²-3x e. (x-5)⁴+(x-3)⁴ = 16

Answer 1

a: \(\Leftrightarrow\left(3x+2\right)\left(5-x\right)=-9x^2+4\)

\(\Leftrightarrow\left(3x+2\right)\left(5-x\right)+\left(3x+2\right)\left(3x-2\right)=0\)

\(\Leftrightarrow\left(3x+2\right)\left(2x+3\right)=0\)

=>x=-2/3 hoặc x=-3/2

b: \(\Leftrightarrow4x\left(x+5\right)+x^2-25=0\)

\(\Leftrightarrow\left(x+5\right)\left(5x-5\right)=0\)

=>x=-5 hoặc x=1

c: \(\Leftrightarrow3x\left(x-1\right)=\left(x-1\right)^2\)

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

=>x=1 hoặc x=-1/2