21. Efectuati produsele:
a) (x+2)(x+3)
b) (x-3)(x+5)
c) (1-2x)(x+7)
d) (3x-5y)(4x+2y)
22. Calculati:
a) (x-1)(x+2)+(3x-1)(2x+5)-3x(x+1)
b) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)
c) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)
d) (2-x)(x+x^2)-x^2(3+x)+8+(x+2)(5+x^2)
Yasmi061:
Dai puţine pentru un asemenea exerciţiu...Nu o să ţi-l rezolve nimeni...
Răspunsuri la întrebare
Răspuns de
56
21. a) (x+2)(x+3)= x²+3x+2x+ 6 b) (x-3)(x+5)= x²+5x-3x-15
=x²+5x+6 = x²+2x-15
c) (1-2x)(x+7)= x+ 7-2x²-14x d) (3x-5y)(4x+2y)= 12x²+6xy-20xy-10y²
=-2x²-13x+ 7 =12x²-14xy-10y²
22. a) (x-1)(x+2)+(3x-1)(2x+5)-3x(x+1)=
( x²+ x- 2)+(6x²+13x- 5)-(3x²+3x)=
x²+ x- 2+ 6x²+13x- 5- 3x²- 3x =
4x²+11x- 7
b) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)=
(x²-4x-21)-(x²+3x+ 2)+(-x²+9x-20)=
x²-4x- 21 -x²- 3x- 2 -x²+ 9x- 20=
-x²+2x-43
c) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)=
(a²+2ab-3b²)+(2a²+3ab-2b²)-(a²-ab-2b²)=
a²+2ab-3b²+2a²+3ab-2b²- a²+ ab+ 2b²=
2a²+6ab-3b²
d) (2-x)(x+x^2)-x^2(3+x)+8+(x+2)(5+x^2)= x^= ? ce putere e
(2x+4x^-x²-
=x²+5x+6 = x²+2x-15
c) (1-2x)(x+7)= x+ 7-2x²-14x d) (3x-5y)(4x+2y)= 12x²+6xy-20xy-10y²
=-2x²-13x+ 7 =12x²-14xy-10y²
22. a) (x-1)(x+2)+(3x-1)(2x+5)-3x(x+1)=
( x²+ x- 2)+(6x²+13x- 5)-(3x²+3x)=
x²+ x- 2+ 6x²+13x- 5- 3x²- 3x =
4x²+11x- 7
b) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)=
(x²-4x-21)-(x²+3x+ 2)+(-x²+9x-20)=
x²-4x- 21 -x²- 3x- 2 -x²+ 9x- 20=
-x²+2x-43
c) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)=
(a²+2ab-3b²)+(2a²+3ab-2b²)-(a²-ab-2b²)=
a²+2ab-3b²+2a²+3ab-2b²- a²+ ab+ 2b²=
2a²+6ab-3b²
d) (2-x)(x+x^2)-x^2(3+x)+8+(x+2)(5+x^2)= x^= ? ce putere e
(2x+4x^-x²-
Răspuns de
31
a) (x+2)(x+3)=x²+2x+3x+6=x²+5x+6
b) (x-3)(x+5)=x²-3x+5x-15=x²+5x-15
c) (1-2x)(x+7)=x-2x²+7-14x=-2x²-13x+7
d) (3x-5y)(4x+2y)=12x²-20xy+6xy-10y²=12x²-14xy-10y²=
22. Calculati:
a) (x-1)(x+2)+(3x-1)(2x+5)-3x(x+1)=
=x²-x+2x-2+6x²-2x+15x-5-3x²-3x=
=4x²+11x-7
b) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)=
=x²-7x+3x-21-x²-x-2x-2-5x-x²-20+4x=
=-x²+2x-43
c) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)=
=a²-ab+3ab-3b²+2a²-ab+4ab-2b²-a²-ab+2ab+2b²=
=2a²+6ab-3b²
d) (2-x)(x+x²)-x²(3+x)+8+(x+2)(5+x²) =
= 2x-x²+2x²-x³-3x²-x³+8+5x+10+x³+2x² =
= 2x-x²+2x²-x³-3x²-x³+5x+x³+2x² =
= 2x-x²+2x²-x³-3x²-x³+5x+x³+2x² =
= -x³+7x+18
b) (x-3)(x+5)=x²-3x+5x-15=x²+5x-15
c) (1-2x)(x+7)=x-2x²+7-14x=-2x²-13x+7
d) (3x-5y)(4x+2y)=12x²-20xy+6xy-10y²=12x²-14xy-10y²=
22. Calculati:
a) (x-1)(x+2)+(3x-1)(2x+5)-3x(x+1)=
=x²-x+2x-2+6x²-2x+15x-5-3x²-3x=
=4x²+11x-7
b) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)=
=x²-7x+3x-21-x²-x-2x-2-5x-x²-20+4x=
=-x²+2x-43
c) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)=
=a²-ab+3ab-3b²+2a²-ab+4ab-2b²-a²-ab+2ab+2b²=
=2a²+6ab-3b²
d) (2-x)(x+x²)-x²(3+x)+8+(x+2)(5+x²) =
= 2x-x²+2x²-x³-3x²-x³+8+5x+10+x³+2x² =
= 2x-x²+2x²-x³-3x²-x³+5x+x³+2x² =
= 2x-x²+2x²-x³-3x²-x³+5x+x³+2x² =
= -x³+7x+18
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