How do I factor
2z^2 + 11z - 21
Please explain it so I understand how you got your answer! Thanks!
2007-09-11 06:18:10 · 6 answers · asked by shauna s 1 in Science & Mathematics ➔ Mathematics
Factors of 2 z ² can only be 2 z and z:-
(2 z------) (z-----)
Factors of 21 are 7 and 3 or 3 and 7
Try 3 and 7:-
(2 z-----3) (z----7)
Have to decide upon signs for 3 and 7 in order to obtain + 11x
Try :-
( 2 z - 3) ( z + 7 ) is correct.
2007-09-11 08:46:07 · answer #1 · answered by Como 7 · 3⤊ 0⤋
2z² + 11z - 21 = 0
The middle term is + 11x
Find the sum of the middle term
Multiply the first term 2 times the last term 21 equals 42 and factor
Factors of 42
1 x 42
2 x 21
3 x 14. . .â. .use these factors
6 x 7
+ 14 and - 3 satisfy the sum of the middle term
insert + 14z and - 3x into the equation
2z² + 14z - 21 = 0
2z² + 14x - 3z - 21 = 0
Group factor
(2z² + 14z) - (3x - 21) = 0
2z(x + 7) - 3(x + 7) = 0
(2x - 3)(x + 7) = 0
- - - - - - - - -s-
2007-09-11 14:16:37 · answer #2 · answered by SAMUEL D 7 · 3⤊ 0⤋
1. 2z^2 + 11z - 21
First: multiply the 1st & 3rd term to get (- 42). Find two numbers that give you (- 42) when multiplied & 11 (2nd term) when added/subtracted. The numbers are (14 & - 3)
Sec: rewrite the expression with the new, middle numbers. Group "like" terms.
2z^2 + 14z - 3z - 21
(2z^2 + 14z) - (3z - 21)
Third: factor both sets of parenthesis.
2z(z + 7) - 3(z + 7)
SOlution: combine the inner term (once) with the outer term.
(z + 7)(2z - 3) or, (2z - 3)(z + 7)
2007-09-11 13:30:50 · answer #3 · answered by ♪♥Annie♥♪ 6 · 2⤊ 0⤋
2z^2 + 11z - 21
= 2z^2 + 14z - 3z - 21
= 2z(z + 7) - 3(z + 7)
= (2z - 3)(z + 7)
2007-09-11 13:29:06 · answer #4 · answered by fofo m 3 · 0⤊ 1⤋
= 2z^2-3z+14z-21
= z(2z-3)+7(2z-3)
= (z+7)(2z-3)
2007-09-11 13:30:22 · answer #5 · answered by ngtuhanh188 3 · 0⤊ 1⤋
try (2z - 3)(z + 7)
2007-09-11 13:22:03 · answer #6 · answered by Chang Y 3 · 0⤊ 1⤋