Mă poate ajuta cineva urgent vă rog
Răspunsuri la întrebare
Răspuns:
Explicație pas cu pas:
8) f · g = ?
a) f = 2-5x+7x² ; g = 4-3x²+x⁴
f · g = ( 2-5x+7x²) · (4-3x²+x⁴) =
= 8-6x²+2x⁴-20x+15x³-5x⁵+28x²-21x⁴+7x⁶=
= 8-20x+22x²+15x³-19x⁴-5x⁵+7x⁶
b) f = 7-x ; g = 343+49x+7x²+x³
f · g = (7-x ) · (343+49x+7x²+x³) =
= 2401+343x+49x²+7x³-343x-49x²-7x³-x⁴ = 2401-x⁴
c) f = x²+2x³-5x⁴ ; g = 3-4x+11x²-x³
f · g = (x²+2x³-5x⁴) · (3-4x+11x²-x³) =
= 3x²-4x³+11x⁴-x⁵+6x³-12x⁴+22x⁵-2x⁶-15x⁴+20x⁵-55x⁶+5x⁷=
= 3x²+2x³-16x⁴+41x⁵-57x⁶+5x⁷
9) a) (x-2)(x³-4x+5) - (x-8)(x+8) =
= x⁴-4x²+5x-2x³+8x-10-x²+64 = x⁴-2x³-5x²+13x+54
b) (x-1)(4-x)(x²-x+3) + (x+2)(x-5) = (4x-x²-4+x)(x²-x+3) + x²-5x+2x-10=
=(5x-x²-4)(x²-x+3)+x²-7x-10 = 5x³-5x²+15x-x⁴+x³-3x²-4x²+4x-12+x²-7x-10=
= -x⁴+6x³-11x²+12x-22
c) 3(x²-5x+1/3) - 2/5(10-15x²)+(x²-x+1)(x+1) =
= 3x²-15x+1-4+6x²+x³+x²-x²-x+x+1 = x³+9x²-15x-2
d) (4-√3x)(4+√3x) - 5(x²-2x+7)+(5x+3)(-2x-1) =
= 16-3x²-5x²+10x-35-10x²-5x-6x-3 = -18x²-x-22