SOLUTION: (9x+7)(7x+5)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: (9x+7)(7x+5)       Log On


   

Question 113570: (9x+7)(7x+5)
Found 2 solutions by stanbon, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
(9x+7)(7x+5)
------
Use FOIL:
F: 9x*7x = 63x^2
O: 9x*5 = 45x
I: 7*7x = 49x
L: 7*5 = 35
----------------
Combine to get 63x^2 + 94x + 35
==================
Cheers,
Stan H.

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

%289x%2B7%29%287x%2B5%29
%2863x%5E2+%2B+45x+%2B49x+%2B35%29
63x%5E2+%2B+94x+%2B35
We can solve it for x if we set this expression equal to 0
63x%5E2+%2B+94x+%2B35+=+0……..use square root formula

x%5B1%2C2%5D=%28-b+%2B-+sqrt+%28b%5E2+-4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29
x%5B1%2C2%5D=%28-94+%2B-+sqrt+%2894%5E2+-4%2A63%2A35+%29%29+%2F+%282%2A63%29
x%5B1%2C2%5D=%28-94+%2B-+sqrt+%288836+-+8820%29%29+%2F+126

x%5B1%2C2%5D=%28-94+%2B-+sqrt+%2816%29%29+%2F+126

x%5B1%2C2%5D=%28-94+%2B-+4%29+%2F+126

x%5B1%5D=%28-94+%2B+4%29+%2F+126
x%5B1%5D=+-90++%2F+126

x%5B1%5D=+-+0.71

x%5B2%5D=%28-94+-+4%29+%2F+126
x%5B2%5D=+-98++%2F+126
x%5B2%5D=+-+0.78

Or, we can do it this way:
%289x%2B7%29%287x%2B5%29+=+0….here we have a product of two binomials set to 0; as we know, this product will be equal to 0 if one binomial or both of them are equal to 0.
9x%2B7+=+0….
9x+=+-7….
x+=+-7%2F9….
x+=+-+0.78………first solution

7x%2B5+=+0….

7x+=+-5….
x+=+-5%2F7….
x+=+-+0.71………..second solution