Toán Lớp 8: Thực hiện các phép tính
a) 2x(x2 -3x +5)
b) (15x3y2 + 10x2y4 +25×3 ) : 5xy2
c)5xy 4xy+1
——+———
X+3. X+3
d) 5. 2
—— – —–
X+1. X-1
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Toán Lớp 8: Thực hiện các phép tính
a) 2x(x2 -3x +5)
b) (15x3y2 + 10x2y4 +25×3 ) : 5xy2
c)5xy 4xy+1
——+———
X+3. X+3
d) 5. 2
—— – —–
X+1. X-1
Comments ( 1 )
Giải đáp+Lời giải và giải thích chi tiết:
$a)2x(x^2-3x+5)=2x^3-6x^2 +10x$
$b) (15x^3y^2+10x^2y^4+25x^3):5xy^2=15x^3y^2:5xy^2+10x^2y^4:5xy^2+25x^3:5xy^2=3x^2+2xy^3+5x^2y$
$c) $ $\dfrac{5xy}{x+3}+$ $\dfrac{4xy+1}{x+3}=$ $\dfrac{5xy+4xy+1}{x+3}=$ $\dfrac{9xy+1}{x+3}$
$d) \dfrac{5}{x+1}-$ $\dfrac{2}{x-1}=$ $\dfrac{5(x-1)}{(x+1)(x-1)}-$ $\dfrac{2(x+1)}{(x+1)(x-1)}=$ $\dfrac{5(x-1)-2(x+1)}{(x+1)(x-1)}=$ $\dfrac{5x-5-2x-2}{(x+1)(x-1)}=$ $\dfrac{3x-7}{(x+1)(x-1)}=$