please help!!
2007-03-09 23:40:41 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Transpose 7x to the other side
3x²+2x-7x-12=0
3x²-5x-12=0
Factor...
(3x+4)(x-3)=0
Theorem: If ab=0 then either a=0 or b=0.
so...
either 3x+4=0 or x-3=0
transposing...
x=-4/3 or x=3
2007-03-10 00:14:25 · answer #1 · answered by forgetfulpcspice 3 · 0⤊ 1⤋
3x^2 + 2x - 12 = 7x == > 3x^2 - 5x - 12 = 0
Thus using the usual resolving formula for a quadratic equation
3x^2 - 5x - 12 = (3x - 4)(x -3) = 0 ==> x = 3 and x = -4/3
2007-03-09 23:46:46 · answer #2 · answered by physicist 4 · 0⤊ 1⤋
3x² + 2x - 12 = 7x
3x² + 2x - 12 - 7x = 7x - 7x
3x² - 5x - 12 = 0
Find the sum of the middle term. Multiply 3 times 12 equal 36
Factors of 36 = 2, 3, 4, 6, 9 12, 18
- 9 + 4 satisfy the sum of the middle term
3x² - 5x - 12 = 0
3x² - 9x + 4x - 12
3x(x - 3) + 4(x - 3)
(3x + 4)(x - 3)
- - - - - - - - -s-
2007-03-10 00:02:14 · answer #3 · answered by SAMUEL D 7 · 0⤊ 1⤋
it is a 2nd degree equation
=>
3x^2 - 5x - 12 =0
Delta = 25 - 4.3.-12 = 169
x1= (5 - 13)/2.3 = - 4/3
x2= 3
2007-03-09 23:48:16 · answer #4 · answered by abd 5 · 0⤊ 0⤋
3x² - 5x - 12 = 0
(3x + 4 ).(x - 3) = 0
x = - 4 / 3, x = 3
2007-03-10 00:06:19 · answer #5 · answered by Como 7 · 0⤊ 1⤋