Đáp án:
Giải thích các bước giải:
CÓ KHOẢNG 5 CÂU MÌNH CHƯA LÀM CHO MÌNH XIN LỖI BẠN NHIỀU LẮM NHÉ!!!!!
câu 1
a 3x^2.(2x^3-x+5)=6x^5-3x^3+15x^2
b (4xy+3y-5x).x^2y=4x^3y^2+3x^2y^2-5x^3y
c (3x-2)(4x+5)-6x(2x-1)=12x^2+15x-8x-10-12x^2+6x=13x-10
d (3x-5)(x^2-5x+7)=3x^3-15x^2+21x-5x^2+25x-35=3x^3-20x^2+46x-35
câu 2
a x.(x+1)-x^2+2=0
=>x^2+x-x^2+2=0=>x+2=0=>x=-2
vậy x=-2
b 2.(3x+2)-(2x+12)=0
=>6x+4-2x-12=0=>4x-8=0=>x=8/4=2
vậy x=2
c 2x^3(2x-3)-x^2(4x^2-6x+2)=0
=>4x^4-6x^3-(4x^4-6x^3+2x^2)=0
=>4x^4-6x^3-4x^4+6x^3-2x^2=0
=>-2x^2=0=>x=0
vậy x=0
d (3x+2)(x-1)-3(x+1)(x-2)=4
=>3x^2-3x+2x-2-(3x^2-3x-2)=4
=>3x^2-3x+2x-2-3x^2+3x+2=4
=>2x=4=>x=2
vậy x=2
baaif 3
a (x+5)^2=x^2+2.x.5+5^2=x^2+10x+25
b (x-3y)^2=x^2-2.x.3y+3y^2=x^2-6xy+9y^2
c (x^2-6z)(x^2+6z)=(x^2)^2-6z^2=x^4-6x^2
d (x+3y)^3=x^3+3.x^2.3y+3.x.3y^2+3y^3=x^3+9x^2y+9xy^2+3y^3
e (2x-y)^3=2x^3-3.2x^2.y+3.2x.y^2-y^3=2x^3-6x^2y+6xy^2-y^3
bài 4
a x^2 +10x+25=x^2+2.x.5+5^2=(x+5)^2
b 16x^2-8x+1=(4x)^2-2.4x.1+1=(4x-1)^2
c 4x^2+12xy+9y^2=(2x)^2+2.2x.3y+(3y)^2=(2x+3y)^2
d x^3+3x^2+3x+1=x^3+3.x^2.1+3.x.1^2+1^3=(x+1)^3
e 27y^3-9y^2+y-1/27=SORRY YOU VERY MUCH!!!!
g 8x^6+12x^4y+6x^2y^2+y^3=SORRY YOU VERY MUCH!!!!
bài 5
a 153^2+94.153+47^2=SORRY YOU VERY MUCH
b 126^2.152.126+5776=SORRY YOU VERY MUCH!!!
c 3^8.5^8-(15^4-1)(15^4+1)=SORRY YOU VERY MUCH!!!
bài 6
a 5x(x-2)-3x^2(x-2)=(5x-3x^2)(x-2)=x(5-3x)(x-2)
b 16x^2-(x^2+4)^2=(16x-x^2+4)(16x+x^2+4)
c 5x^2-5xy+7y-7x=5x(x-y)+7(y-x)=5x(x-y)-7(x-y)=(x-y)(5x-7)
d 3x^2-8x+4=3x^2-6x-2x+4=3x(x-2)-2(x-2)=(3x-2)(x-2)
e x^4+64=x^4+16x^2+64-16x^2=(x^2)^2+2.x^2.8+8^2-16x^2=(x^2+8)^2-(4x)^2=(x^2+8-4x)(x^2+8+4x)
