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Mathematics 7 Online
OpenStudy (anonymous):

Factor completely: 4x^2 + 25x + 6 A. (4x + 1)(x + 6) B.(4x + 6)(x + 1) C.(2x + 3)(2x + 2) D.(2x + 6)(2x + 1)

Parth (parthkohli):

I see.. This is easy once you understand

OpenStudy (anonymous):

How would I do the ( x + a) and (x+b)

Parth (parthkohli):

1) Find the product of numerical coefficients of a and c first.

Parth (parthkohli):

I mean product of a and c.

OpenStudy (anonymous):

How do I do that?

OpenStudy (anonymous):

ok..

OpenStudy (anonymous):

Um.. I don't know.

Parth (parthkohli):

a is 4 and c is 6...

OpenStudy (anonymous):

How did you get that?

Parth (parthkohli):

\(\Large \color{Black}{\Rightarrow ax^2 + bx + c }\) Trinomials are in this form. Remember? compare this with the question

OpenStudy (anonymous):

okay so a would be ..4 and c would be 6.

OpenStudy (anonymous):

I see. okay now what?

Parth (parthkohli):

Yes, find their product.

OpenStudy (anonymous):

Product..

OpenStudy (anonymous):

of 4 ..

OpenStudy (anonymous):

2

OpenStudy (anonymous):

6 would be 3.

Parth (parthkohli):

no no.... 4 * 6

OpenStudy (anonymous):

24

Parth (parthkohli):

Ok, now that you have done it, then find two numbers that have the sum as b and the product as the product of a and c.

OpenStudy (anonymous):

b = 25 right?

Parth (parthkohli):

Correct. Find two number such that the sum equals b and the product equals a and c.

OpenStudy (anonymous):

So, finding a product of 24.

OpenStudy (anonymous):

12 * 2?

Parth (parthkohli):

Two numbers that have a sum of 25 and their multiplication equals 6 * 4.

Parth (parthkohli):

I see that the numbers are 24 and 1.

OpenStudy (anonymous):

Ah because 24 * 1 = 24 and 24+1 = 25.

Parth (parthkohli):

Now, just split the middle term like this. \(\Large \color{Black}{\Rightarrow 4x^2 + 24x + 1x + 6 }\) Factor first two terms and last two terms. \(\Large \color{Black}{\Rightarrow 4x(x + 6) + 1(x + 6) }\) Now just group them. \(\Large \color{Black}{\Rightarrow (4x + 1)(x + 6)}\)

OpenStudy (anonymous):

okay can we try another one?

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