題題試過自己做做到亂曬龍咁
求高手出馬
PS. Steps are needed...

GM7811 - 834 @ N8x :題題試過自己做做到亂曬龍咁
求高手出馬
PS. Steps are needed...

1.9(m+n)²-12(m+n)(m-2n)+4(m-2n)²

=9(m²+2mn+n²)-12(m²-mn-2n²)+4(m²-4mn+4n²)

=9m²+18mn+9n²-12m²+12mn+24n²+4m²-16mn+16n²

=9m²-12m²+4m²+18mn+12mn-16mn+9n²+24n²+16n²

=m²-14mn+49n²

=(m-7n)²<-呢part唔知要唔要填=.=

HU7527 :1.9(m+n)²-12(m+n)(m-2n)+4(m-2n)²

=9(m²+2mn+n²)-12(m²-mn-2n²)+4(m²-4mn+4n²)

=9m²+18mn+9n²-12m²+12mn+24n²+4m²-16mn+16n²

=9m²-12m²+4m²+18mn+12mn-16mn+9n²+24n²+16n²

=m²-14mn+49n²

=(m-7n)²<-呢part唔知要唔要填=.=

最後果個要
難怪我做唔倒. 我一開始就張所有2次方夾埋一個括號度做

Q2:
49x⁶+140x³y+100y²
=(7x³)²+2(7x³)(10y)+(10y)²
=(7x³+10y)²

Q3:
25-(h²+18hk+81k²)
=25-(h+9k)²
=5²-(h+9k)²
=(5+h+9k)(5-h-9k)

Q4:
64p²-224pq+196q²-484x²
=4(16p²-56pq+49q²-121x²)
=4[(4p-7q)²-121x²]
=4[(4p-7q)²-(11x)²]
=4(4p-7q+11x)(4p-7q-11x)

Q5:
16x²+46xy-35y²-8x+5y
=(8x-5y)(2x+7y)-8x+5y
=(8x-5y)(2x+7y)+(8x-5y)(-1)
=(8x-5y)(2x+7y-1)

HU7527 :

GM7811 - 834 @ N8x :題題試過自己做做到亂曬龍咁
求高手出馬
PS. Steps are needed...

1.9(m+n)²-12(m+n)(m-2n)+4(m-2n)²

=9(m²+2mn+n²)-12(m²-mn-2n²)+4(m²-4mn+4n²)

=9m²+18mn+9n²-12m²+12mn+24n²+4m²-16mn+16n²

=9m²-12m²+4m²+18mn+12mn-16mn+9n²+24n²+16n²

=m²-14mn+49n²

=(m-7n)²<-呢part唔知要唔要填=.=

乜去到咁遠呀 ...

1.
9(m+n)²-12(m+n)(m-2n)+4(m-2n)²
= [(3)(m+n)]² - 2[(3)(m+n)][(2)(m-2n)] + [(2)(m-2n)]²
= [(3m+3n) - (2m-4n)]²
= (m + 7n)²

唔係咁咩 ?

第一題唔係乘返開再抽公因子咩

GNZ9068 :第一題唔係乘返開再抽公因子咩

(a+b)^2=a^2+2ab+b^2
sub a=(m+n),b=(m-2n)
咁就搞掂

brianlhm :

GNZ9068 :第一題唔係乘返開再抽公因子咩

(a+b)^2=a^2+2ab+b^2
sub a=(m+n),b=(m-2n)
咁就搞掂

自己試過咁做. 但系一拆就亂曬