Answer:
Step-by-step explanation:
9x⁴ – 2x² – 7 = 0
Let's say that u = x²:
9u² – 2u – 7 = 0
Factor:
(u – 1) (9u + 7) = 0
u = 1, -7/9
Since u = x²:
x² = 1, -7/9
x = ±1, ±i √(7/9)
X^2-14x+49=0
Factor
(x-7)(x-7)
Check
-7-7=-14
-7*-7=49
Use ZPP
x-7=0
x=7
Final answer: x=7
Answer:
3(3a - 6b + 7c )
Step-by-step explanation:
The greatest common factor of 9, 18 and 21 is 3
Factor out 3 from each term
9a - 18b + 21c
= 3(3a - 6b + 7c) ← in factored form
Answer:

Step-by-step explanation:
2(x^2 + 10x + 25) + 3
2x^2 + 20x + 50 + 3
2x^2 + 20x + 53
Use this systems of equations to solve:
x = first antifreeze
y = second antifreeze

Isolate y.
x + y = 15
Subtract x from both sides.
y = -x + 15
Substitute y into the other equation.
.2x + .12(-x + 15) = .18(15)
Simplify.
.2x - .12x + 1.8 = 2.7
Subtract 1.8 from both sides.
.08x = .9
Divide both sides by .08
x = 11.25
Substitute x in the equation that we isolated y in.
y = -11.25 + 15
y = 3.75
11.25 L of the first antifreeze and 3.75 L of the second.