因式分解?

2007-04-21 8:28 pm
因式分解下列各式:(步驟)

1. (j+k)^2-(l-m)^2
2. (p+q)^2-(p-q)^2
3. (3r+4s)^2-(5t-6s)^2
4. 36a^2-25(3b-c)^2
5. 100(2d-e)^2-49f^2
6. (5g-6h)^2-16(4g-3h)^2

^2 =2次方

回答 (3)

2007-04-21 8:43 pm
✔ 最佳答案
1.(j+k-l+m)(j+k+l-m)
2.(p+q-p+q)(p+q+p-q)=(2q)(2p)=4qp
3.(3r+4s-5t+6s)(3r+4s+5t-6s)=(3r+10s-5t)(3r-2s+5t)
4.t)(4a)^2-(5(3b-c))^ 2=(4a+15b-c)(4a-15b+c)
5.(10(2d-e))^2-(7f)^2=(20d-10e-7f)(20d-10e+7f)
6.(5g-6h)^2-(4(4g-3h))^2=(5g-6h-16g+12h)(5g-6h+16g-12h)=(6h-11g)(21g-18h)
參考: 自己
2007-04-21 9:29 pm
希望可以help you

1.(j+k)^2-(1-m)^2
=([j+k)+(1-m)][(j+k)-(1-m)]
=(j+k+1-m)(j+k-1+m)
=(j+k)^2

2(p+q)^2-(p-q)^2
=[(p+q)+(p-q)][(p+q)-(p-q)]
=(p+q+p-q)(p+q-p+q)
=2p2q

2007-04-21 9:10 pm
因式分解下列各式:(步驟)

題1. (j+k)² -(l-m)²
*〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
= 〔j+k+(l-m)〕〔j+k-(l-m)〕
= (j+k+l-m)(j+k-l+m)
──────────────────────────────────────
題2. (p+q)² -(p-q)²
*〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
= 〔p+q+(p-q)〕〔p+q-(p-q)〕
=(p+q+p-q)(p+q-p+q)
= (2p)(2q)
= 4pq
───────────────────────────────────────
題3. (3r+4s)² -(5t-6s)²
 *〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
=〔3r+4s+(5t-6s)〕〔3r+4s-(5t-6s)〕
=(3r+4s+5t-6s)(3r+4s-5t+6s)
= (3r+5t-2s)(3r-5t+10s)
──────────────────────────────────────
題4. 36a² -25(3b-c)²
= (6a)² - 〔5(3b-c)〕²
*〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
= 〔6a+5(3b-c)〕〔6a-5(3b-c)〕
= (6a+15b-5c)(6a-15b+5c) 
───────────────────────────────────────
題5. 100(2d-e)² -49f²
= 〔10(2d-e)〕² - (7f)²
*〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
= 〔10(2d-e)+7f〕〔10(2d-e)-7f〕
= (20d-10e+7f)(20d-2010e-7f)
───────────────────────────────────────
題6. (5g-6h)² -16(4g-3h)²
= (5g-6h)² - 〔4(4g-3h)〕²
*〔運用恆等式:a² - b² ≡ (a+b)(a-b)〕
=(5g-6h+4(4g-3h)〕〔5g-6h-4(4g-3h)〕
=(5g-6h+16g-12h)(5g-6h-16g-12h)
=(21g-18h)(-11g-18h)  
───────────────────────────────────────
參考: 自己(2007年理科應屆會考生)


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