A. (5r - 3)^2
B. (3r - 5)^2
C. (25r + 9)^2
D. (25r - 9)^2
How do I solve this 25r^2 - 30r + 9 equals?
2008-09-21 2:10 pm
回答 (8)
2008-09-21 2:26 pm
✔ 最佳答案
25r^2-30r+925r^2-15r-15r+9
5r(5r-3r)-3(5r-3)
(5r-3)(5r-3)
(5r-3)^2
A
參考: I did this by factor-by-grouping.
2008-09-21 9:26 pm
25r² - 30r = - 9
r² - 6/5r = - 9/25
r² - 3/5r = - 9/25 + (- 3/5)²
r² - 3/5r = - 9/25 + 9/25
(r - 3/5)² = 0
r - 3/5 = 0
Factor:
= r - 3/5
= 5r - 3
Answer: A. (5r - 3)²
Proof:
= (5r - 3)(5r - 3)
= 25r² - 15r - 15r + 9
= 25r² - 30r + 9
r² - 6/5r = - 9/25
r² - 3/5r = - 9/25 + (- 3/5)²
r² - 3/5r = - 9/25 + 9/25
(r - 3/5)² = 0
r - 3/5 = 0
Factor:
= r - 3/5
= 5r - 3
Answer: A. (5r - 3)²
Proof:
= (5r - 3)(5r - 3)
= 25r² - 15r - 15r + 9
= 25r² - 30r + 9
2008-09-21 9:23 pm
Equating this equation=0,r1=r2=3/5,then 25[(r-3/5)^2]=(5r-3)^2.
CHECK:25r^2-30r+9
CHECK:25r^2-30r+9
2008-09-21 9:19 pm
the answer actually (5r-3)(5r-3)=0
so that the best answer is A, (5r-3)^2
so that the best answer is A, (5r-3)^2
2008-09-21 9:18 pm
25r^2 - 30r + 9
5*5 = 25 3*3 = 9
2*5*3 = 30
(5r - __)(5r - __)
(5r - 3)(5r- 3)
Answer A
5*5 = 25 3*3 = 9
2*5*3 = 30
(5r - __)(5r - __)
(5r - 3)(5r- 3)
Answer A
2008-09-21 9:13 pm
a
2008-09-21 11:11 pm
25r^2 - 30r + 9
= 25r^2 - 15r - 15r + 9
= (25r^2 - 15r) - (15r - 9)
= 5r(5r - 3) - 3(5r - 3)
= (5r - 3)(5r - 3)
= (5r - 3)^2
(answer A)
= 25r^2 - 15r - 15r + 9
= (25r^2 - 15r) - (15r - 9)
= 5r(5r - 3) - 3(5r - 3)
= (5r - 3)(5r - 3)
= (5r - 3)^2
(answer A)
2008-09-21 9:27 pm
A. (5r-3)^2
(5r-3)(5r-3)
25r^2-30r+9
do the F.I.L.O.
first in, last out
5r * 5r, then 5r * -3, then 5r * -3, then -3*-3
(5r-3)(5r-3)
25r^2-30r+9
do the F.I.L.O.
first in, last out
5r * 5r, then 5r * -3, then 5r * -3, then -3*-3
收錄日期: 2021-05-01 11:11:21
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