Toán Lớp 8: rút gọn phân thức:
a)((2x+3)^2-x^2)/(x^2-1)
b)(x^3-3x^2-x+3)/(x^2-3x)
__________
không làm tắt.
Leave a reply
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.
Toán Lớp 8: rút gọn phân thức:
a)((2x+3)^2-x^2)/(x^2-1)
b)(x^3-3x^2-x+3)/(x^2-3x)
__________
không làm tắt.
Comments ( 2 )
a, ((2x+3)^2-x^2)/(x^2-1)
=((2x+3-x)(2x+3+x))/((x-1)(x+1))
=((x+3)(3x+3))/((x-1)(x+1))
=(3(x+1)(x+3))/((x-1)(x+1))
=(3(x+3))/(x-1)
=(3x+9)/(x-1)
b, (x^3-3x^2-x+3)/(x^2-3x)
=(x^2(x-3)-(x-3))/(x(x-3))
=((x-3)(x^2-1))/(x(x-3))
=(x^2-1)/x
a)frac{(2x + 3)^{2} – x^{2}}{x^{2} – 1}
=frac{(2x + 3 – x)(2x + 3 + x)}{(x – 1)(x + 1)}
=frac{(x + 3)(3x + 3)}{(x – 1)(x + 1)}
=frac{3(x + 3)}{x – 1} = frac{3x + 9}{x – 1}
b)frac{x^{3} – 3x^{2} – x + 3}{x^{2} – 3x}
=x^{3} – 3x^{2} – x + 3
=x^{2}(x – 3) – (x – 3)
=(x – 3)(x^{2} – 1)
=(x – 3)(x^{2} – 1)x^{2} – 3x
=x(x – 3)
=>text{Có kết quả} frac{x^{2} – 1}{x}