Answer:
Step-by-step explanation:
45
Answer:
(4x-7)(4x+7)
Step-by-step explanation:
This is called the Difference of Two Squares (DOTS).
These are the conditions that must be met for DOTS to work:
•There must be 2 terms.
•They must be separated by a negative sign.
•Each term must be a perfect square.
First, you have to find 2 square numbers that times together to make 16.
4×4=16
As we want 16x², you just need to make the 4 become 4x:
4x times 4x equals 16x²
Then, find 2 squares that times together to make 49.
7×7=49
You can put the two squares into a bracket with the x variable first, then the number:
(4x-7)(4x+7)
In the brackets, you always put the negative sign in the first one and then the plus sign in the second one.
You can double check your answer by expanding it back out again using FOIL:
F-First
O-Outer
I-Inner
L-Last
Times the First two in the two brackets:
4x times 4x equals 16x²
Times the Outer two:
4x times 7 equals 28x
Times the Inner two:
-7 times 4x equals -28x
Times the Last two:
-7 times 7 equals -49
Form an equation:
16x²+28x-28x-49
The 28x cancel out to leave:
16x²-49
Hope this helps :)
Answer:
Length 37 cm, width 25 cm.
Step-by-step explanation:
Let the original dimensions be length x and width x - 12 cms.
The new dimensions will be length (x - 2) and width (x - 12 - 2) = x-14 cm.
So , from the areas, we have:
x(x - 12) - (x - 2)(x - 14) = 120
x^2 - 12x - (x^2 - 16x + 28) = 120
-12x + 16x - 28 = 120
4x = 148
x = 37 cms
So the length was 37 cm and the width was 37-12 = 25 cm.
Answer:
x=-2
Step-by-step explanation:
Since it is an equilateral triangle (note the little lines across the legs of corner 2) the other angle must be 69° as well.
That leaves 180-69-69 = 42 for ∠2.
So x + 44 = 42 => x = 42-44 = -2.
