Question

tìm x

b) (x + 3)² - (x - 4)( x + 8) = 1;

c) 3(x + 2)² + (2x - 1)² - 7(x + 3)(x - 3) = 36;     

d)(x - 3)(x² + 3x + 9) + x(x + 2)(2 - x) = 1;

e) (x + 1)³ - (x - 1)³ - 6(x - 1)² = -19.

hihi

Answer 1

b)(x+3)²-(x-4)(x+8)=1

\(\Rightarrow\)x²+6x+9-(x²+8x-4x-32)=1

⇒x²+6x+9-x²-8x+4x+32=1

⇒2x+41=1

\(\Rightarrow\)2x+41-1=0

\(\Rightarrow\)2x+40=0

⇒2x=-40

\(\Rightarrow\)x=\(\dfrac{-40}{2}\)

⇒x=-20