Step-by-step explanation:
x² - 2x - 15 = 0
x1 = 5
x2 = -3
Answer:
(64,86.5)
Step-by-step explanation:
find the case where he gets 70 and the case where he gets 79
if his average is 70:
(75+62+85+2x)/5=70
(222+2x)/5=70
222+2x=350
2x=128
x=64
if his average is 79:
(75+62+85+2x)/5=79
(222+2x)/5=79
222+2x=395
222+2x=395
2x=173
x=86.5
Check the picture below
notice, using the 30-60-90 rule, since that triangle is a 30-60-90 triangle, we get 11 = 2x
5.4x10^11 metres per second or 540,000,000,000 metres per second
Answer:
y = 5, -4
Step-by-step explanation:
To solve proportions you cross-multiply.

Now that we have 8 = y^2 - y - 12, we must make the entire trinomial equal to 0 by subtracting 8 from both sides.
y^2 - y - 20 = 0
Factor the trinomial.
(y - 5)(y + 4) = 0
Make both factors equal to 0 to solve for both values of y.
- y - 5 = 0 --> y = 5
- y + 4 = 0 --> y = -4
y = 5, -4