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

Toán Lớp 8: giúp mình với bài 4:Tìm x a)x^2 -25-(x+5)=0 b)3x(x-2) – x+2=0 c)x(x – 4)-2x+8=0 d)3x(x+5)- 3x- 15=0 e) ( 3x – 1)^2 – (x+5)^2=0 f) (2x-

Home/ Toán Lớp 8: giúp mình với bài 4:Tìm x a)x^2 -25-(x+5)=0 b)3x(x-2) – x+2=0 c)x(x – 4)-2x+8=0 d)3x(x+5)- 3x- 15=0 e) ( 3x – 1)^2 – (x+5)^2=0 f) (2x-

Toán Lớp 8: giúp mình với bài 4:Tìm x a)x^2 -25-(x+5)=0 b)3x(x-2) – x+2=0 c)x(x – 4)-2x+8=0 d)3x(x+5)- 3x- 15=0 e) ( 3x – 1)^2 – (x+5)^2=0 f) (2x-

Tháng Sáu 10, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: giúp mình với bài 4:Tìm x
a)x^2 -25-(x+5)=0
b)3x(x-2) – x+2=0
c)x(x – 4)-2x+8=0
d)3x(x+5)- 3x- 15=0
e) ( 3x – 1)^2 – (x+5)^2=0
f) (2x- 1)^2 – (x-3)^2=0

Comments ( 2 )

  1. buianhtuan
    buianhtuan
    10 Tháng Sáu, 2022 at 4:36 chiều
    Reply
    Giải đáp:
    ↓↓
    Lời giải và giải thích chi tiết:
    a)
    x^2 -25-(x+5)=0
    ⇒x^2 -5^2-(x+5)=0
    ⇒(x-5)(x+5)-(x+5)=0
    ⇒(x+5)(x-5-1)=0
    ⇒(x+5)(x-6)=0
    ⇒ \(\left[ \begin{array}{l}x+5=0\\x-6=0\end{array} \right.\) 
    ⇒ \(\left[ \begin{array}{l}x=-5\\x=6\end{array} \right.\) 
    Vậy \(\left[ \begin{array}{l}x=-5\\x=6\end{array} \right.\)
    b)
    3x(x-2) – x+2=0
    ⇒3x(x-2)-(x-2)=0
    ⇒(x-2)(3x-1)=0
    ⇒ \(\left[ \begin{array}{l}x-2=0\\3x-1=0\end{array} \right.\)
    ⇒ \(\left[ \begin{array}{l}x=2\\x= \frac{1}{3}\end{array} \right.\)
    Vậy \(\left[ \begin{array}{l}x=2\\x=\frac{1}{3}\end{array} \right.\)
    c)
    x(x – 4)-2x+8=0
    ⇒x(x-4)-2(x-4)=0
    ⇒(x-4)(x-2)=0
    ⇒ \(\left[ \begin{array}{l}x-4=0\\x-2=0\end{array} \right.\)
    ⇒ \(\left[ \begin{array}{l}x=4\\x=2\end{array} \right.\)
    Vậy \(\left[ \begin{array}{l}x=4\\x=2\end{array} \right.\)
    d)
    3x(x+5)- 3x- 15=0
    ⇒3x(x+5)-3(x+5)=0
    ⇒(x+5)(3x-3)=0
    ⇒ \(\left[ \begin{array}{l}x+5=0\\3x-3=0\end{array} \right.\)
    ⇒ \(\left[ \begin{array}{l}x=-4\\x=1\end{array} \right.\)
    Vậy \(\left[ \begin{array}{l}x=-4\\x=1\end{array} \right.\)
    e)
    (3x-1)^2-(x+5)^2=0
    ⇒(3x-1-x-5)(3x-1+x+5)=0
    ⇒(2x-6)(4x+4)=0
    ⇒ \(\left[ \begin{array}{l}2x-6=0\\4x+4=0\end{array} \right.\)
    ⇒ \(\left[ \begin{array}{l}x=3\\x=-1\end{array} \right.\)
    Vậy \(\left[ \begin{array}{l}x=3\\x=-1\end{array} \right.\)
    f)
    (2x- 1)^2 – (x-3)^2=0
    ⇒(2x-1-x+3)(2x-1+x-3)=0
    ⇒(x+2)(3x-4)=0
    ⇒ \(\left[ \begin{array}{l}x+2=0\\3x-4=0\end{array} \right.\)
    ⇒ \(\left[ \begin{array}{l}x=-2\\x= \frac{4}{3}\end{array} \right.\)
    Vậy \(\left[ \begin{array}{l}x=-2\\x=\frac{4}{3}\end{array} \right.\)

  2. tuminh25
    tuminh25
    10 Tháng Sáu, 2022 at 4:36 chiều
    Reply
    Các bước giải:
    a)x^2 -25-(x+5)=0
    ⇒x^2 -5^2-(x+5)=0
    ⇒(x-5)(x+5)-(x+5)=0
    ⇒(x+5)(x-5-1)=0
    ⇒(x+5)(x-6)=0
    ⇒\(\left[ \begin{array}{l}x+5=0\\x-6=0\end{array} \right.\) 
    ⇒\(\left[ \begin{array}{l}x=-5\\x=6\end{array} \right.\) 
    Vậy x=-5 hoặc x=6
    b)3x(x-2) – x+2=0
    ⇒3x(x-2)-(x-2)=0
    ⇒(x-2)(3x-1)=0
    ⇒\(\left[ \begin{array}{l}x-2=0\\3x-1=0\end{array} \right.\)
    ⇒\(\left[ \begin{array}{l}x=2\\x= \frac{1}{3}\end{array} \right.\)
    Vậy x=2 hoặc x= $\frac{1}{3}$ 
    c)x(x – 4)-2x+8=0
    ⇒x(x-4)-2(x-4)=0
    ⇒(x-4)(x-2)=0
    ⇒\(\left[ \begin{array}{l}x-4=0\\x-2=0\end{array} \right.\)
    ⇒\(\left[ \begin{array}{l}x=4\\x=2\end{array} \right.\)
    Vậy x=4 hoặc x=2
    d)3x(x+5)- 3x- 15=0
    ⇒3x(x+5)-3(x+5)=0
    ⇒(x+5)(3x-3)=0
    ⇒\(\left[ \begin{array}{l}x+5=0\\3x-3=0\end{array} \right.\)
    ⇒\(\left[ \begin{array}{l}x=-4\\x=1\end{array} \right.\)
    Vậy x=-4 hoặc x=1
    e)(3x-1)^2-(x+5)^2=0
    ⇒(3x-1-x-5)(3x-1+x+5)=0
    ⇒(2x-6)(4x+4)=0
    ⇒\(\left[ \begin{array}{l}2x-6=0\\4x+4=0\end{array} \right.\)
    ⇒\(\left[ \begin{array}{l}x=3\\x=-1\end{array} \right.\)
    Vậy x=3 hoặc x=-1
    f) (2x- 1)^2 – (x-3)^2=0
    ⇒(2x-1-x+3)(2x-1+x-3)=0
    ⇒(x+2)(3x-4)=0
    ⇒\(\left[ \begin{array}{l}x+2=0\\3x-4=0\end{array} \right.\)
    ⇒\(\left[ \begin{array}{l}x=-2\\x= \frac{4}{3}\end{array} \right.\)
    Vậy x=-2 hoặc x= $\frac{4}{3}$

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

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