ok you have:

x^2 + 2x – 15

first you know that x^2 is just x * x.

now you need to find the signs. you know that since the last number is negative ( -15) one must be positive, and one must be negative.

( x + ___ ) ( x – ___ )

now you need 2 numbers, when the product is -15, and the added amount is 2.

in this case (-3)*5 = 15

and (-3) + 5 = 2

so your two numbers are -3 and 5. put them into the equation respectfully.

(x + 5)(x – 3) and you get your answer.

this is factoring polynomials

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in foil, like the equation you gave (x-7)(x-2)

you do [x*x] + [x(-2)] + [(-7)x] + [(-7)(-2)]

which you get:

x^2 – 2x – 7x +14

x^2 -9x + 14

You need to have the larger number be positive, because the two is positive.

Also, 7X2 is 14, not fifteen, so seven and two won’t work.

2) ?

3) (-3x-1)(x-1)

4)?

Sorry. I suck at math. Hope i helped abit