Answer:
It is 5. I got it right on khan academy! Thanks for the answer!
Step-by-step explanation:
Using the distributive property we know we distribute by multiplying the outside values to those inside of the parentheses
outside values: 2
inside values: 5 and r
now multiply out inside values by the outside values
2x5 = 10
2xr = 2r
now plug these values back in for the inside values and take away the outside value and the parentheses
so 2(5+r) using the distribution property is 10+2r
For x^2-49
this is a diffarence of two perfect squares. I suggest that this is memorised.
a^2-b^2=(a-b)(a+b)
so x^2-7^2=(x-7)(x+7)
so to solve x^2+x-56 you want to find out what two numbers add to 1 and multiply to make -56
since -56 is negative we know that the two number are difarent signs so that eliminatess answers B and D.
if we try answer C -8+7=-1 so the answer is not C because we want +1 not -1
then we see that 8+(-7)=1 so the answer is A
