first: add 7x to each side. Then divide both sides by 9
second: subtract 9x+16 from each side. Then divide both sides by 15
1) 2x²-7x-15
2) 9x²+24x+16
Can you show me all the steps...i don't know how to do it...Thankyou!!:)
5 answers
we have to factor not solve
1. Y = 2x^2-7x-15 = 0.
Use the AC method of factoring:
A*C = 2*-15 = -30 = 1*-30 = 3*-10.
Choose the pair of factors whose sum = B(-7): 3, and -10.
2x^2 + (3x-10x) - 15 = 0.
Group the 4 terms into 2 factorable pairs:
(2x^2-10x) + (3x-15)
2x(x-5) + 3(x-5)
(x-5) is common to both terms. So we factor out(x-5):
(x-5)(2x+3) = 0
x-5 = 0
X = 5.
2x+3 = 0
2x = -3
X = -1.5.
Solution set: X = 5, and -1.5.
2. 9x^2+24x+16 = 0.
The given expression is a perfect square: 9x^2+24x+16 = (3x+4)^2 = 0.
(3x+4)^2 = 0
Take sgrt of both sides:
+-(3x+4) = 0
3x+4 = 0
3x = -4
X = -1 1/3 = -1.33333.
-3x-4 = 0
-3x = 4
X = -1 1/3 = -1.33333.
Solution X = -1.33333, and -1.33333.
Note: The given expression was set to zero, because the solutions are x-intercepts and Y = 0 at the x-intercepts.
Use the AC method of factoring:
A*C = 2*-15 = -30 = 1*-30 = 3*-10.
Choose the pair of factors whose sum = B(-7): 3, and -10.
2x^2 + (3x-10x) - 15 = 0.
Group the 4 terms into 2 factorable pairs:
(2x^2-10x) + (3x-15)
2x(x-5) + 3(x-5)
(x-5) is common to both terms. So we factor out(x-5):
(x-5)(2x+3) = 0
x-5 = 0
X = 5.
2x+3 = 0
2x = -3
X = -1.5.
Solution set: X = 5, and -1.5.
2. 9x^2+24x+16 = 0.
The given expression is a perfect square: 9x^2+24x+16 = (3x+4)^2 = 0.
(3x+4)^2 = 0
Take sgrt of both sides:
+-(3x+4) = 0
3x+4 = 0
3x = -4
X = -1 1/3 = -1.33333.
-3x-4 = 0
-3x = 4
X = -1 1/3 = -1.33333.
Solution X = -1.33333, and -1.33333.
Note: The given expression was set to zero, because the solutions are x-intercepts and Y = 0 at the x-intercepts.
9x^2+24x+16. Factor only.
9x^2+24x+16 = (3x+4)^2 = (3x+4)(3x+4).
9x^2+24x+16 = (3x+4)^2 = (3x+4)(3x+4).
Thankyou so much!!