It is a rectangular pyramid
should i explain?
fell free to tell me if it doesn't make sense :)
-3√45 + 3√20 = -3√(9 · 5) + 3√(4 · 5) =
= -3√(3² · 5) + 3√(2² · 5) =
= -3 · 3√5 + 3 · 2√5 =
= -9√5 + 6√5 = -3√5 ← the end
X^2(x+2)-4(x+2)
(x^2-4) (x+2) = 0
do you have to keep going/?
or thats all they want?
7x³ = 28x is our equation. We want its solutions.
When you have x and different powers, set the whole thing equal to zero.
7x³ = 28x
7x³ - 28x = 0
Now notice there's a common x in both terms. Let's factor it out.
x (7x² - 28) = 0
As 7 is a factor of 7 and 28, it too can be factored out.
x (7) (x² - 4) = 0
We can further factor x² - 4. We want a pair of numbers that multiply to 4 and whose sum is zero. The pairs are 1 and 4, 2 and 2. If we add 2 and -2 we get zero.
x (7) (x - 2) (x + 2) = 0
Now we use the Zero Product Property - if some product multiplies to zero, so do its pieces.
x = 0 -----> so x = 0
7 = 0 -----> no solution
x - 2 = 0 ----> so x = 2 after adding 2 to both sides
x + 2 = 0 ---> so = x - 2 after subtracting 2 to both sides
Thus the solutions are x = 0, x = 2, x = -2.