this equation is from a math.com test. It said the answer is x= -2 and 1. I don't know how they came to that conclusion. Please help.
2006-11-15 10:08:25 · 9 answers · asked by vision_quest11 1 in Science & Mathematics ➔ Mathematics
(x-7)(x-5)
so x= +7, or +5
2006-11-15 10:10:25 · answer #1 · answered by Mike P 3 · 0⤊ 1⤋
The easiest way to do these equations for me (without using a graphing calculator) is to make a box with 4 squares in them. Take the x squared and put it in the top left box and the -35 in the bottom right. Then on the left outside and the top outside of the box figure out what would multiply each other to get the answer in the box. Well, X times X= Xsquared and 7x5=35. To get -2x you have to have -7 and 5 which gives the -2 when added and -35 when multiplied. This would be alot easier to explain when drawn out. your answer would then give you (x + 5)(x - 7)=0, therefore, X= 7, -5. I will try to make into the square.
x - 7
x xsquared -7x
+
5 5x -35
2006-11-15 10:24:15 · answer #2 · answered by Proverbs 2 · 0⤊ 0⤋
well, try filling it in. -2 squared is 4. 2 times -2 is -4.
so 4 minus -4 - 35 = -23. i dont think thats right.
and how about 1. 1 squared is 1. 2 times 1 is 2.
so 1 - 2 - 35 = -34. i dont think thats right, either.
but what about x= -5?
lets see....
-5 squared is 25. 2 times -5 is -10.
so 25 minus -10 - 35 does equal 0! wow! -5 is the answer!
2006-11-15 10:15:51 · answer #3 · answered by abcdgoodall 4 · 0⤊ 0⤋
Just by looking, -5 is an obvious answer without putting any paper to pencil (or fingertip to calculator).
x^2 - 2x -35 = 0
x^2 - 2x = 35
-5^2 - 2(-5) = 35
25 - (-10) = 35
25 + 10 = 35
35 = 35
Then 7 looks like another solution.
x^2 - 2x = 35
7^2 - 2(7) = 35
49 - 14 = 35
35 = 35
Trust your common sense on this one.
2006-11-15 10:18:59 · answer #4 · answered by Mark C 1 · 1⤊ 0⤋
X=7 or X=-5
(7x7)-(2x7)-35=0
(49-14)-35=0
35-35=0
(-5x-5)-(2x-5)-35=0
25- (-10)-35=0
35-35=0
2006-11-15 10:16:33 · answer #5 · answered by Anonymous · 0⤊ 0⤋
x^2-2x-35=0
(x-7)(x+5)=0
x-7=0
x=7
x+5=0
x=-5
The answer given is wrong. That happens more than you might think.
2006-11-15 10:38:35 · answer #6 · answered by yupchagee 7 · 0⤊ 0⤋
x^2-2x-35
factor: (x-7)(x+5)
ans: 7 and 5
i don't know how they got 1 and -2. that's wrong
2006-11-15 10:11:02 · answer #7 · answered by 7 · 0⤊ 0⤋
dont know
2006-11-15 10:10:43 · answer #8 · answered by Anonymous · 0⤊ 1⤋
I don't know that is weird, Idk if it can be solved.
Sorry
2006-11-15 10:14:16 · answer #9 · answered by Kourtney H 1 · 0⤊ 0⤋