Answer:
10
Step-by-step explanation:

If you were to factor you would do what my teacher likes to call reverse foil so it would look like this (x-9)(x+4) so what you do is you brainsrorm to see what multiplies what to get that and 9*4=36 so that is how you factor -36 to find the -9
Hope this helps if I'm correct if not I will try to find the answer
Answer:
61.25%
Step-by-step explanation:
How many ml of 20 percent acid should be added to pure acid
to make 70 ml of 30 percent acid?
:
let x = amt of 20% mixture
then
(70-x) = amt of pure acid
:
0.20x + (70-x) =0 .30(70)
0.20x + 70 - x = 21
= 21 - 70
-0.8x =-49
x = 61.25%
x = +61.25 ml of 20% stuff
One solution to your problem is 15(1-2x)
Answer:
B
Step-by-step explanation:
Given a quadratic equation in standard form
ax² + bx + c = 0 ( a ≠ 0 )
Then the discriminant is
Δ = b² - 4ac
• If b² - 4ac > 0 then 2 real irrational roots
• If b² - 4ac > 0 and a perfect square then 2 real rational roots
• If b² - 4ac = 0 then 1 real double root
• If b² - 4ac < 0 then 2 complex roots
Given
x² + 3x - 7 = 0 ← in standard form
with a = 1, b = 3, c = - 7 , then
b² - 4ac
= 3² - (4 × 1 × - 7) = 9 + 28 = 37
Since b² - 4ac > 0 then 2 real irrational roots