a) (2x^2-3)-x^2 (5x+1)+x^2
b)3x (x-2)-5x (1-x)-8 (x^2-3)
c)(x+3) (x^2-3x+9)-(54+x^3)
d) (2x+y) (4x^2-2xy+y^2)-(4x^2+2xy+y^2)
a) (2x^2-3)-x^2 (5x+1)+x^2
b)3x (x-2)-5x (1-x)-8 (x^2-3)
c)(x+3) (x^2-3x+9)-(54+x^3)
d) (2x+y) (4x^2-2xy+y^2)-(4x^2+2xy+y^2)
Đáp án:
c) -27
Giải thích các bước giải:
\(\begin{array}{l}
a)(2{x^2} – 3) – {x^2}(5x + 1) + {x^2}\\
= 2{x^2} – 3 – 5{x^3} – {x^2} + {x^2}\\
= – 5{x^3} + 2{x^2} – 3\\
b)3x(x – 2) – 5x(1 – x) – 8({x^2} – 3)\\
= 3{x^2} – 6x – 5x + 5{x^2} – 8{x^2} + 24\\
= – 11x + 24\\
c)(x + 3)({x^2} – 3x + 9) – (54 + {x^3})\\
= {x^3} + 27 – 54 – {x^3}\\
= – 27\\
d)(2x + y)(4{x^2} – 2xy + {y^2}) – (4{x^2} + 2xy + {y^2})\\
= 8{x^3} + {y^3} – 4{x^2} – 2xy – {y^2}
\end{array}\)