16: 49x2 + 36 = 84x
-6/7, 0
6/7
-7, -6
17: 25x2 - 10x + 1 = 0
-5, 1
1, 5
1/5
18: 12x2 + 2x - 4 = 0
1/2, 0
-2/3, 1/2
2/3, 1/2, 0
19: (a + b)2 + 20(a + b) + 100 = 0
a + b = _______
-10
10
-10, 10
20: 25(a + b)2 - 10(a + b) = -1
a + b = ______
5
1/5
5, 1/5
2007-08-20 13:54:42 · 4 answers · asked by kitara 1 in Science & Mathematics ➔ Mathematics
16)6/7
17)1/5
18)-2/3,1/2
19)-10
20)1/5
2007-08-20 14:02:44 · answer #1 · answered by moona 4 · 0⤊ 1⤋
I will give you a hand (free)...let's look at the first problem:
49x^2 + 36 = 84x
49x^2 - 84x + 36 = 0
(7x - 6) (7x - 6) = 0 after some trial and error. You can also use the quadratic equation if you need to arrive to the answer quickly.
so, the final answer is x = 6/7 , 6/7 as a double root.
Good luck with the rest of the homework!
2007-08-20 21:04:59 · answer #2 · answered by alrivera_1 4 · 1⤊ 0⤋
16:
49x^2 + 36 = 84x
(7x - 6)(7x - 6) = 0
7x = 6
x = 6/7
17:
25x^2 - 10x + 1 = 0
(5x - 1)^2 = 0
x = 1/5
18:
12x^2 + 2x - 4 = 0
6x^2 + x - 2 = 0
(3x + 2 )( 2x - 1) = 0
x = -2/3, 1/2
19:
(a + b)^2 + 20(a + b) + 100 = 0
( (a+b) + 10 )^2 = 0
(a + b) = -10
20:
25(a + b)^2 - 10(a + b) = -1
(5(a+b) - 1)^2 = 0
(a + b) = 1/5
2007-08-20 21:09:21 · answer #3 · answered by vlee1225 6 · 0⤊ 1⤋
The people who answered your question should be criticized for not noticing that you have asked us (in three separate questions) to do problems 6 through 20 for you.
2007-08-20 21:28:06 · answer #4 · answered by Tony 7 · 1⤊ 1⤋