Tìm x biết:
c) 2x mũ 2 + 3(x – 1)(x + 1) = 5x(x + 1);
d) (8 – 5x)((x + 2) + 4(x – 2)(x + 1) + (x – 2)(x + 2);
e) 4(x – 1)( x + 5) – (x +2)(x + 5) = 3(x – 1)(x + 2).
Tìm x biết:
c) 2x mũ 2 + 3(x – 1)(x + 1) = 5x(x + 1);
d) (8 – 5x)((x + 2) + 4(x – 2)(x + 1) + (x – 2)(x + 2);
e) 4(x – 1)( x + 5) – (x +2)(x + 5) = 3(x – 1)(x + 2).
Đáp án:
Giải thích các bước giải:2x^2 +3x^2-3=5x^2 +5x
5x^2-3=5x^2+5x
5x=-3
x=-3/5
b)khong co dau bang
c)4x^2+16x-20-x^2-7x=3x^2+3x-6
3x^2 + 9x – 20=3x^2 +3x -6
6x=14
x=7/3
Giải thích các bước giải:
c, 2x²+3(x-1)(x+1)= 5x(x+1)
⇔2x²+3(x²-1)=5x²+5x
⇔2x²+3x²-3=5x²+5x
⇔2x²+3x²-5x²-5x=3
⇔-5x=3
⇔x=-3/5
Vậy x=-3/5
d, (8-5x)(x+2)+4(x-2)(x+1) +(x-2)(x+2)
=8x+16-5x²-10x+4x²-4x-8+x²-4
= -6x+4
e, 4(x-1)(x+5)-(x+2)(x+5)= 3(x-1)(x+2)
⇔4x²+20x-4x-20-x²-5x-2x-10=3x²+6x-3x-6
⇔4x²+20x-4x-x²-5x-2x-3x²-6x+3x= 20+10-6
⇔6x=24
⇔x=4