Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: tìm x: a)(2x-5).(2x+5)-4.(x+2)^2=0 b)2.(x+5)^2-(x-3)^2-(x+2).(x-2)

Toán Lớp 8: tìm x:
a)(2x-5).(2x+5)-4.(x+2)^2=0
b)2.(x+5)^2-(x-3)^2-(x+2).(x-2)

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    a) (2x-5) . (2x+5) – 4 (x+2)^2 = 0
    ⇔ 4x^2 – 25 – 4 (x^2+4x+4) = 0
    ⇔ 4x^2 – 25 – 4x^2 – 16x – 16 = 0
    ⇔ -16x – 41 = 0
    ⇔ -16x = 41
    ⇔ x = -41/16
    Vậy x = -41/16
    b) 2(x+5)^2 – (x-3)^2 – (x+2) (x-2) = 0
    ⇔ 2 (x^2+10x+25) – (x^2-6x+9) – (x^2-4) = 0
    ⇔ 2x^2 + 20x + 50 – x^2 + 6x – 9 – x^2 + 4 = 0
    ⇔ 26x + 45 = 0
    ⇔ 26x = -45
    ⇔ x = -45/26
    Vậy x = -45/26
     

  2. $a)(2x-5).(2x+5)-4.(x+2)^2=0$
    $⇔4x^2-25-4(x^2+4x+4)=0$
    $⇔4x^2-4x^2 -16x-25-16=0$
    $⇔-16x=41$
    $⇔x=\dfrac{-41}{16}$
    Vậy $S=\{\dfrac{-41}{16}\}$
    $b)2.(x+5)^2-(x-3)^2-(x+2).(x-2)=0$
    $⇔2(x^2+10x+25)-(x^2-6x+9)-(x^2-4)=0$
    $⇔2x^2+20x+50-x^2+6x-9-x^2+4=0$
    $⇔(2x^2-x^2-x^2)+(20x+6x)=-45$
    $⇔26x=-45$
    $⇔x=\dfrac{-45}{26}$
    Vậy $S=\{\dfrac{-45}{26}\}$

Leave a reply

222-9+11+12:2*14+14 = ? ( )

About Ngọc Sa