i suck at this
5a2 + 3a - 2
2007-07-08 05:19:39 · 6 answers · asked by andy s 2 in Science & Mathematics ➔ Mathematics
5a^2 + 3a - 2
5a^2 + 5a - 2a - 2
5a(a+1)-2(a+1)
(5a-2)(a+1)
Here's a method where you just memorize and don't have to think about.
Divide the expression by 5 so that your leading coefficient is 1.
a^2 + 3/5a - 2/5
Set the expression equal to 0.
a^2 + 3/5a - 2/5 = 0
Add 2/5 on both sides.
a^2 + 3/5a = 2/5
Add b^2/4 on both sides. (The usual equation is ax^2+bx+c=0)
b = 3/5
b^2/4 = 9/100
a^2 + 3/5x +9/100 = 2/5 + 9/100
Now divide the b term by 2.
b/2 = 3/10
So then you apply that in the form of (x+b/2)^2
(a+3/10)^2 = 2/5 + 9/100
9/100 + 2/5 = 49/100
(a+3/10)^2 = 49/100
a + 3/10 = 7/10
a = 4/10 or 2/5
Remember that a square root is also negative.
a + 3/10 = -7/10
a = -1
Now think of what plus a gives you 0.
(5*2/5 - 2) = 0
-1+1 = 0
So your binomials multiplied are
(5a-2)(a+1)
Also exclude the 0 because I needed it only to find the roots of a.
If you don't understand that method just e-mail me.
As a reminder, the method where you don't have to think would be best if you're inexperienced. If you're experienced, the method of factoring using your head is faster.
2007-07-08 05:25:05 · answer #1 · answered by UnknownD 6 · 0⤊ 0⤋
Observe that a=-1 is a trivial root and you obtain the factorization:
5 a^2 + 3 a - 2 = (a+1) (5a -2)
2007-07-08 05:26:24 · answer #2 · answered by DrGerard 5 · 0⤊ 0⤋
5a^2 +3a -2 = (5a -2)*(a +1)
2007-07-08 05:24:40 · answer #3 · answered by nyphdinmd 7 · 0⤊ 0⤋
(a+1)(5a-2)=0
a=-1 and 2/5
2007-07-08 05:24:48 · answer #4 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋
a(5a+3)-2
2007-07-08 05:23:41 · answer #5 · answered by tab7240 2 · 0⤊ 1⤋
5a^2+3a-2
=5a^2+5a-2a-2
=5a(a+1)-2(a+1)
=(a+1)(5a-2)
2007-07-08 05:24:34 · answer #6 · answered by alpha 7 · 0⤊ 0⤋