Tìm x, biết: (5x + 1)^2 ‒ (5x + 3)(5x ‒ 3) = 30.
Giải thích
(5x + 1)2 ‒ (5x + 3)(5x ‒ 3) = 30
25x2+10x+1−(25x2−9)=30
25x2+10x+1−25x2+9=30
10x+10=30
10x = 30 ‒ 10
10x=20
x =2
Vậy x = 2.
(5x + 1)2 ‒ (5x + 3)(5x ‒ 3) = 30
25x2+10x+1−(25x2−9)=30
25x2+10x+1−25x2+9=30
10x+10=30
10x = 30 ‒ 10
10x=20
x =2
Vậy x = 2.