Question

tìm x

a) (2x+5)(2x-7)-(-4x-3)²=16

b) (8x²+3)(8x²-3)-(8x²-1)²=22

c) 49x²+14x+1=0

d) (x-1)³-x(x-2)²-(x-2)=0

giúp mình với nha

Answer 1

c) 49x²+14x+1=0

=>(7x+1)²=0

= > 7x+1=0

=> 7x=-1

=> x=-\(\dfrac{1}{7}\)