Examples with solutions for Factoring Trinomials: Solving the problem

Exercise #1

x25x50=0 x^2-5x-50=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x25x50=0 x^2-5x-50=0 is a quadratic equation that can be solved using quick factoring:

x25x50=0{??=50?+?=5(x10)(x+5)=0 x^2-5x-50=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=-50\\ \underline{?}+\underline{?}=-5\end{cases}\\ \downarrow\\ (x-10)(x+5)=0 and therefore we get two simpler equations from which we can extract the solution:

(x10)(x+5)=0x10=0x=10x+5=0x=5x=10,5 (x-10)(x+5)=0 \\ \downarrow\\ x-10=0\rightarrow\boxed{x=10}\\ x+5=0\rightarrow\boxed{x=-5}\\ \boxed{x=10,-5} Therefore, the correct answer is answer C.

Answer

x=10,x=5 x=10,x=-5

Exercise #2

x219x+60=0 x^2-19x+60=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x219x+60=0 x^2-19x+60=0 is a quadratic equation that can be solved using quick factoring:

x219x+60=0{??=60?+?=19(x4)(x15)=0 x^2-19x+60=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=60\\ \underline{?}+\underline{?}=-19\end{cases}\\ \downarrow\\ (x-4)(x-15)=0 and therefore we get two simpler equations from which we can extract the solution:

(x4)(x15)=0x4=0x=4x15=0x=15x=4,15 (x-4)(x-15)=0 \\ \downarrow\\ x-4=0\rightarrow\boxed{x=4}\\ x-15=0\rightarrow\boxed{x=15}\\ \boxed{x=4,15} Therefore, the correct answer is answer A.

Answer

x=15,x=4 x=15,x=4

Exercise #3

x2+10x24=0 x^2+10x-24=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x2+10x24=0 x^2+10x-24=0 is a quadratic equation that can be solved using quick factoring:

x2+10x24=0{??=24?+?=10(x+12)(x2)=0 x^2+10x-24=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=-24\\ \underline{?}+\underline{?}=10\end{cases}\\ \downarrow\\ (x+12)(x-2)=0 and therefore we get two simpler equations from which we can extract the solution:

(x+12)(x2)=0x+12=0x=12x2=0x=2x=12,2 (x+12)(x-2)=0 \\ \downarrow\\ x+12=0\rightarrow\boxed{x=-12}\\ x-2=0\rightarrow\boxed{x=2}\\ \boxed{x=-12,2} Therefore, the correct answer is answer B.

Answer

x=2,x=12 x=2,x=-12

Exercise #4

x22x3=0 x^2-2x-3=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x22x3=0 x^2-2x-3=0 is a quadratic equation that can be solved using quick factoring:

x22x3=0{??=3?+?=2(x3)(x+1)=0 x^2-2x-3=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=-3\\ \underline{?}+\underline{?}=-2\end{cases}\\ \downarrow\\ (x-3)(x+1)=0 and therefore we get two simpler equations from which we can extract the solution:

(x3)(x+1)=0x3=0x=3x+1=0x=1x=1,3 (x-3)(x+1)=0 \\ \downarrow\\ x-3=0\rightarrow\boxed{x=3}\\ x+1=0\rightarrow\boxed{x=-1}\\ \boxed{x=-1,3} Therefore, the correct answer is answer B.

Answer

x=3,x=1 x=3,x=-1

Exercise #5

x27x+12=0 x^2-7x+12=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x27x+12=0 x^2-7x+12=0 is a quadratic equation that can be solved using quick factoring:

x27x+12=0{??=12?+?=7(x3)(x4)=0 x^2-7x+12=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=12\\ \underline{?}+\underline{?}=-7\end{cases}\\ \downarrow\\ (x-3)(x-4)=0 and therefore we get two simpler equations from which we can extract the solution:

(x3)(x4)=0x3=0x=3x4=0x=4x=3,4 (x-3)(x-4)=0 \\ \downarrow\\ x-3=0\rightarrow\boxed{x=3}\\ x-4=0\rightarrow\boxed{x=4}\\ \boxed{x=3,4} Therefore, the correct answer is answer A.

Answer

x=3,x=4 x=3,x=4

Exercise #6

x23x18=0 x^2-3x-18=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x23x18=0 x^2-3x-18=0 is a quadratic equation that can be solved using quick factoring:

x23x18=0{??=18?+?=3(x6)(x+3)=0 x^2-3x-18=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=-18\\ \underline{?}+\underline{?}=-3\end{cases}\\ \downarrow\\ (x-6)(x+3)=0 and therefore we get two simpler equations from which we can extract the solution:

(x6)(x+3)=0x6=0x=6x+3=0x=3x=6,3 (x-6)(x+3)=0 \\ \downarrow\\ x-6=0\rightarrow\boxed{x=6}\\ x+3=0\rightarrow\boxed{x=-3}\\ \boxed{x=6,-3} Therefore, the correct answer is answer A.

Answer

x=3,x=6 x=-3,x=6

Exercise #7

x23x18=0 x^2-3x-18=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x23x18=0 x^2-3x-18=0 is a quadratic equation that can be solved using quick factoring:

x23x18=0{??=18?+?=3(x6)(x+3)=0 x^2-3x-18=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=-18\\ \underline{?}+\underline{?}=-3\end{cases}\\ \downarrow\\ (x-6)(x+3)=0 and therefore we get two simpler equations from which we can extract the solution:

(x6)(x+3)=0x6=0x=6x+3=0x=3x=6,3 (x-6)(x+3)=0 \\ \downarrow\\ x-6=0\rightarrow\boxed{x=6}\\ x+3=0\rightarrow\boxed{x=-3}\\ \boxed{x=6,-3} Therefore, the correct answer is answer A.

Answer

x=3,x=6 x=-3,x=6

Exercise #8

x2+9x+20=0 x^2+9x+20=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x2+9x+20=0 x^2+9x+20=0 is a quadratic equation that can be solved using quick factoring:

x2+9x+20=0{??=20?+?=9(x+5)(x+4)=0 x^2+9x+20=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=20\\ \underline{?}+\underline{?}=9\end{cases}\\ \downarrow\\ (x+5)(x+4)=0 and therefore we get two simpler equations from which we can extract the solution:

(x+5)(x+4)=0x+5=0x=5x+4=0x=4x=4,5 (x+5)(x+4)=0 \\ \downarrow\\ x+5=0\rightarrow\boxed{x=-5}\\ x+4=0\rightarrow\boxed{x=-4}\\ \boxed{x=-4,-5} Therefore, the correct answer is answer A.

Answer

x=4,x=5 x=-4,x=-5

Exercise #9

x2+10x+16=0 x^2+10x+16=0

Video Solution

Step-by-Step Solution

Let's observe that the given equation:

x2+10x+16=0 x^2+10x+16=0 is a quadratic equation that can be solved using quick factoring:

x2+10x+16=0{??=16?+?=10(x+2)(x+8)=0 x^2+10x+16=0 \longleftrightarrow\begin{cases}\underline{?}\cdot\underline{?}=16\\ \underline{?}+\underline{?}=10\end{cases}\\ \downarrow\\ (x+2)(x+8)=0 and therefore we get two simpler equations from which we can extract the solution:

(x+2)(x+8)=0x+2=0x=2x+8=0x=8x=2,8 (x+2)(x+8)=0 \\ \downarrow\\ x+2=0\rightarrow\boxed{x=-2}\\ x+8=0\rightarrow\boxed{x=-8}\\ \boxed{x=-2,-8} Therefore, the correct answer is answer B.

Answer

x=8,x=2 x=-8,x=-2

Exercise #10

x21=0 x^2-1=0

Video Solution

Step-by-Step Solution

Let's solve the given equation:

x21=0 x^2-1=0 We will do this simply by isolating the unknown on one side and taking the square root of both sides:

x21=0x2=1/x=±1 x^2-1=0 \\ x^2=1\hspace{6pt}\text{/}\sqrt{\hspace{4pt}}\\ \boxed{x=\pm1}

Therefore, the correct answer is answer A.

Answer

x=±1 x=\pm1

Exercise #11

x2+x2=0 x^2+x-2=0

Video Solution

Answer

(x1)(x+2)=0 (x-1)(x+2)=0

Exercise #12

x2+6x+9=0 x^2+6x+9=0

Video Solution

Answer

x=3 x=-3

Exercise #13

x28x+16=0 x^2-8x+16=0

Video Solution

Answer

x=4 x=4