QUESTION IMAGE
Question
*1. which of the following is the correct factored form of $6m^2 - m - 12$?
a. $(2m + 3)(3m - 4)$
b. $(2m - 3)(3m + 4)$
c. $(6m - 3)(m + 4)$
d. $(6m - 4)(m + 3)$
*2. which of the following is the correct factored form of $4a^2 - ab - 15b^2$?
a. $(2a + 3b)(2a - 5b)$
b. $(2a - 3b)(2a + 5b)$
c. $(4a + 3b)(a - 5b)$
d. $(4a - 3b)(a + 5b)$
*3. which of the following is the correct factored form of $4a^2 - 6ab + 2b^2$?
a. $(2a + b)(2a + b)$
b. $(a + 2b)(4a + b)$
c. $2(2a + b)(a + b)$
d. $2(2a - b)(a - b)$
Problem 1: Factoring \(6m^2 - m - 12\)
Step 1: Multiply \(a\) and \(c\)
For \(ax^2+bx+c\), here \(a = 6\), \(b=-1\), \(c = -12\). Multiply \(a\times c=6\times(-12)=-72\).
Step 2: Find two numbers
Find two numbers that multiply to \(-72\) and add to \(b=-1\). The numbers are \(-9\) and \(8\) (since \(-9\times8=-72\) and \(-9 + 8=-1\)).
Step 3: Split the middle term
Rewrite the middle term: \(6m^2-9m + 8m-12\).
Step 4: Group and factor
Group as \((6m^2-9m)+(8m - 12)\). Factor out \(3m\) from first group and \(4\) from second: \(3m(2m - 3)+4(2m - 3)\). Then factor out \((2m - 3)\): \((2m - 3)(3m + 4)\).
Step 1: Multiply \(a\) and \(c\)
For \(ax^2+bx+c\) (here \(x=a\), \(a = 4\), \(b=-1\), \(c=-15\)). \(a\times c=4\times(-15)=-60\).
Step 2: Find two numbers
Find two numbers that multiply to \(-60\) and add to \(b = -1\). The numbers are \(-6\) and \(5\) (since \(-6\times5=-60\) and \(-6 + 5=-1\)).
Step 3: Split the middle term
Rewrite the middle term: \(4a^2-6ab+5ab - 15b^2\).
Step 4: Group and factor
Group as \((4a^2-6ab)+(5ab - 15b^2)\). Factor out \(2a\) from first group and \(5b\) from second: \(2a(2a - 3b)+5b(2a - 3b)\). Then factor out \((2a - 3b)\): \((2a - 3b)(2a + 5b)\). Wait, no, wait, let's re - check. Wait, \(4a^2 - ab-15b^2\), \(a = 4\), \(c=-15\), \(ac=-60\). The correct numbers: Let's try again. \(4a^2 - ab-15b^2\), we can also use the formula for factoring \(ax^2+bx + c\) where \(x=a\). Let's use the method of factoring by grouping correctly. Let's find two numbers that multiply to \(4\times(-15b^2)=-60b^2\) and add to \(-b\). The numbers are \(-6b\) and \(5b\) (since \(-6b\times5b=-30b^2\)? No, wait, no, \(a = 4\), \(c=-15b^2\), so \(ac=4\times(-15b^2)=-60b^2\). The middle term is \(-ab=-1ab\). So we need two terms with \(a\) and \(b\) such that their product is \(-60b^2\) and sum is \(-b\). Let's take \(-6ab\) and \(5ab\) (since \(-6ab\times5ab=-30a b^2\)? No, I made a mistake earlier. Wait, correct approach: Let's use the formula \((ma+nb)(pa+qb)=mpa^2+(mq+np)ab+nqb^2\). We need \(mp = 4\), \(nq=-15\), \(mq+np=-1\). Let's try \(m = 4\), \(p = 1\), \(n=-5\), \(q = 3\). Then \(mq+np=4\times3+(-5)\times1=12 - 5 = 7\) no. Try \(m = 2\), \(p = 2\), \(n=-5\), \(q = 3\). \(mq+np=2\times3+(-5)\times2=6 - 10=-4\) no. Try \(m = 4\), \(p = 1\), \(n = 5\), \(q=-3\). \(mq+np=4\times(-3)+5\times1=-12 + 5=-7\) no. Try \(m = 2\), \(p = 2\), \(n = 3\), \(q=-5\). \(mq+np=2\times(-5)+3\times2=-10 + 6=-4\) no. Wait, earlier mistake: Let's do it again. \(4a^2 - ab-15b^2\). Multiply \(a = 4\), \(c=-15\), \(ac=-60\). Find two numbers that multiply to \(-60\) and add to \(-1\). The numbers are \(-6\) and \(5\) (since \(-6\times5=-30\)? No, no, \(ac = 4\times(-15)=-60\), so the two numbers should multiply to \(-60\) and add to \(-1\). The numbers are \(-6\) and \(5\) (because \(-6\times5=-30\)? No, I am confused. Wait, let's use the quadratic formula for \(4a^2 - ab-15b^2 = 0\) (treating \(b\) as constant). \(a=\frac{b\pm\sqrt{b^2-4\times4\times(-15b^2)}}{2\times4}=\frac{b\pm\sqrt{b^2 + 240b^2}}{8}=\frac{b\pm\sqrt{241b^2}}{8}\)? No, that's not right. Wait, I think I made a mistake in the options. Wait the options are: A. \((2a + 3b)(2a - 5b)\), B. \((2a - 3b)(2a + 5b)\), C. \((4a + 3b)(a - 5b)\), D. \((4a - 3b)(a + 5b)\). Let's expand option B: \((2a - 3b)(2a + 5b)=4a^2+10ab-6ab - 15b^2=4a^2 + 4ab-15b^2\) no. Option C: \((4a + 3b)(a - 5b)=4a^2-20ab+3ab-15b^2=4a^2-17ab-15b^2\) no. Option D: \((4a - 3b)(a + 5b)=4a^2+20ab-3ab-15b^2=4a^2 + 17ab-15b^2\) no. Option A: \((2a + 3b)(2a - 5b)=4a^2-10ab+6ab-15b^2=4a^2-4ab-15b^2\) no. Wait, maybe the original problem is \(4a^2+ab - 15b^2\)? If that's the case, then \(ac = 4\times(-15)=-60\), numbers \(9\) and \(-8\). Then \(4a^2+9ab-8ab-15b^2=a(4a + 9b)-b(8a + 15b)\) no. Wait, maybe I misread the problem. Wait the problem is \(4a^2 - ab - 15b^2\). Let's try option B: \((2a - 3b)(2a + 5b)=4a^2+10ab-6ab-15b^2=4a^2 + 4ab-15b^2\) (close but not). Option C: \((4a + 3b)(a - 5b)=4a^2-20ab+3ab-15b^2=4a^2-17ab-15b^2\). Option D: \((4a - 3b)(a + 5b)=4a^2+20ab-3ab-15b^2=4a^2 + 17ab-15b^2\). Option A: \((2a + 3b)(2a - 5b)=4a^2-10ab+6ab-15b^2=4a^2-4ab-15b^2\). Wait, maybe the correct answer is B? Wait…
Step 1: Factor out GCF
First, factor out the greatest common factor, which is \(2\): \(2(2a^2-3ab + b^2)\).
Step 2: Factor the quadratic
Factor \(2a^2-3ab + b^2\). Multiply \(a = 2\), \(c = 1\), \(ac = 2\). Find two numbers that multiply to \(2\) and add to \(-3\). The numbers are \(-1\) and \(-2\). Rewrite middle term: \(2a^2-2ab - ab + b^2\). Group: \((2a^2-2ab)+(-ab + b^2)\). Factor out \(2a\) from first group and \(-b\) from second: \(2a(a - b)-b(a - b)\). Factor out \((a - b)\): \((2a - b)(a - b)\). Then multiply by the GCF \(2\): \(2(2a - b)(a - b)\).
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B. \((2m - 3)(3m + 4)\)