Posted by John on Saturday, December 29, 2012 at 10:27am.
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
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.
9x^2+24x+16. Factor only.
9x^2+24x+16 = (3x+4)^2 = (3x+4)(3x+4).
Thankyou so much!!
Related Questions
Algebra - need help in solving by substitution. We all have different steps and ...
Math - Hello, Having trouble with this one... Solve the inequality: (2x-3)(4x)+x...
Maths - is this correct... (3x^2+4x-3)^2-(3x^2-x+2)^2 then is it this (9x^4+24x^...
algebra - Reduce answers to lowest terms. 1.) 2x/2x^2+5x-3 + 5/x^2-9 = 2.) x-3/...
algebra - can you check my answers? i have to write the slope intercept form of ...
algebra 2 - find all the zeroes of: x^5-3x^4-24x^3-72x^2-25x+75=0 5x^5-20x^4-40x...
math - can you check my answers? i have to write the clop intercept form of the ...
Algebra (Re.: Reiny) - The fact that there was that nice symmetry to the ...
Algebra 1 lvl 1 - Hi, I have a test tomorrow and our teacher gave us a huge ...
pre-calc Question on a previous question - On the question below, Bob Pursley ...
For Further Reading
