Toán Lớp 8: a)x^2-1 b)x^2-4 c)x^3-1 d)x^3+1 e)x^2-5x+4 f)x^2-x-2 g)x^2-x-12 h)3x^2-2x-8 giúp vs

Question

Toán Lớp 8:  a)x^2-1 b)x^2-4 c)x^3-1 d)x^3+1 e)x^2-5x+4 f)x^2-x-2 g)x^2-x-12 h)3x^2-2x-8 giúp vs

huenthanh97 · Answer

a) $x^{2}$ $-^{}$ $1^{}$ = $(x-1)(x+1)^{}$    b) $x^{2}$ $-^{}$ $4^{}$ = $x^{2}$ $-^{}$ $2^{2}$ =$(x-2)(x+2)^{}$   c) $x^{3}$ $-^{}$ $1^{}$ = $(x-1)(x^{2}+x+1)^{}$   d) $x^{3}$ $+^{}$ $1^{}$ = $(x+1)(x^{2}-x+1)^{}$   e) $x^{2}$ $-^{}$ $5x^{}$ $+^{}$ $4^{}$ = ($x^{2}$ $-^{}$ $1x^{}$) $-^{}$ ($4x^{}$ $+^{}$ $4^{}$) =  $(x-1)(x-4)$   f) $x^{2}$ $-^{}$ $x^{}$ $-^{}$ $2^{}$ = ($x^{2}$ $+^{}$ $x^{}$) $-^{}$ ($x^{}$+$2^{}$) = $(x+1)(x-2)^{}$   g) $x^{2}$ $-^{}$ $x^{}$ $-^{}$ $12^{}$ = ($x^{2}$ $+^{}$ $3x^{}$) $-^{}$ ($4x^{}$+$12^{}$) = $(x+3)(x-4)^{}$   h) $3x^{2}$ $-^{}$ $2x^{}$ $-^{}$ $8^{}$ = ($3x^{2}$ $-^{}$ $6x^{}$) $-^{}$ ($6x^{}$ $-^{}$ $8^{}$) = $(x-2)(3x+4)^{}$

minhtuyethue · Answer

Giải đáp+Lời giải và giải thích chi tiết:    a) x&sup2; - 1   = x&sup2; - 1&sup2;   = (x - 1)(x + 1)   b) x&sup2; - 4   = x&sup2; - 2&sup2;   = (x - 2)(x + 2)   c) x&sup3; - 1   = x&sup3; - 1&sup3;   = (x - 1)(x&sup2; + x + 1)   d) x&sup3; + 1   = x&sup3; + 1&sup3;   = (x + 1)(x&sup2; - x + 1)   e) x&sup2; - 5x + 4   = (x&sup2; - 4x) - (x - 4)   = x(x - 4) - (x - 4)   = (x - 4)(x - 1)   f) x&sup2; - x - 2   = (x&sup2; - 2x) + (x - 2)   = x(x - 2) + (x - 2)   = (x - 2)(x + 1)   g) x&sup2; - x - 12   = (x&sup2; - 4x) + (3x - 12)   = x(x - 4) + 3(x - 4)   = (x - 4)(x + 3)   h) 3x&sup2; - 2x - 8   = (3x&sup2; + 4x) - (6x + 8)   = x(3x + 4) - 2(3x + 4)   = (x - 2)(3x + 4)